For a more concise version for people who don't need as much explanation, click here.
Here are step-by-step instructions for converting your English-language Dell Axim X30 PDA to Japanese. I found this info online, tried it myself, and it worked. I've tried to make this clearer and more explicit than what I found, so it'll be useful to people who might not be so confident about tinkering with their OS. The same method should work for any other language for which an updated ROM is available.
First, a few caveats.
The Risk: It worked for me, but I'm not knowledgeable enough to be able to guarantee that the conversion will work for you, nor can I be of much help troubleshooting if it doesn't. I'm not an expert--you should use your own judgement in deciding whether or not to attempt this. First off, Dell doesn't want you futzing around with their OS--doing so will void your warranty. If it doesn't work at all, you should be able to back-up to your previous (English) OS, in which case you'll still have a working English PDA, just like you started with, but you won't have a working Japanese PDA. If you buy a PDA just to convert to Japanese, therefore, you're taking a risk that you'll be stuck with an English machine you can no longer return. On the other hand, while I don't think it's likely (remembering that I'm not an expert), attempting this conversion might completely destroy your Axim, leaving you with a very expensive paperweight. So read these instructions and consider the risks carefully before trying this. Again, I didn't think it was too dangerous to try myself, and many other people have done this, but if you choose to do it you are taking a risk, and if it doesn't work I will not be responsible for your loss. If you decide to try this, you're doing it at your own risk. To be absolutely clear, I am not recommending that you try this procedure; I'm providing information, with no guarantee, and you must decide for yourself whether or not to use it.
The cost: A successful conversion will completely wipe your Dell's memory. Everything on it will be lost. Back everything up by sync before you begin. Also, note that some programs designed for the English OS may not work on a Japanized Dell.
The necessary conditions: Finally, the way this works, you can do it only if your Axim's ROM is an older version than the newest English update available on the website (check System\System Information under the settings menu on your Axim to see what version you've got). For example, if your Axim is A05 and the latest update is A06, it'll work. If your machine is A06 already, though, it won't, because the updater will decide you've already got A06 and quit. There are a couple of workarounds for this--see the notes near the bottom of this page.
1. Download and install XVI32 Hex Editor (get the free version; google it if link goes bad).
2. Download and save to your desktop the latest English and Japanese system updaters from Dell, taking note of which filename is for the English and which for the Japanese (see note below for other languages or if these links no longer work).
3. Click on the downloaded English .exe file to start it. The installer will create a folder for the new files on your PC--accept the default and make a note of where this folder is (e.g., in mine, it created C:\Dell\Drives\R101483 for the English). Keep clicking OK until you get to DO YOU WANT TO UPDATE ROM. EXTREMELY IMPORTANT: When you get to DO YOU WANT TO UPDATE ROM choose NO. For DO YOU WANT TO BACKUP/RESTORE A ROM choose YES then choose to SAVE a backup. If the Japanese conversion doesn't work or if you ever want to go back to English, you'll need to use the backup you're saving now. In fact, make another copy on a CD and keep it someplace safe in case your hard drive ever crashes. Then do Step 3 for the Japanese .exe file.
4. Go into the folder created for the Japanese version (refer to those notes about filenames you took in Step 2 and about folder locations in Step 3), open the ROMS folder, open the Japanese folder, and you'll see two .IMG files. The only difference in their names is that one has a C in the middle and the other an N. Choose the C if you have the combo (Wi-Fi and Bluetooth) version, N if you have the version without Wi-Fi and Bluetooth. Right click on the appropriate file, choose "Open with" and, if XVI32 Hex Editor is shown choose it, otherwise click "Choose program" and browse to the location of XVI32 and choose it (it's probably on your desktop). Click OK to open with XVI32 Hex Editor. Size the window to fit in half your monitor and put it in the bottom half of your screen.
Then do the same for the English version and put it in the top half of your screen.
5. This is where you do surgery on your OS. In the Japanese (bottom) version, click on the first square in the upper left of the main window to choose it. The note in the bar at the bottom left of the window should tell you that you're at "Adr Hex 0." From the Edit menu, select "Block <n> chars...", then in the pop-up window enter 100, then click OK. You've just selected the first 100 characters of the code; they should turn red. Then delete them (click the "X" button in the toolbar at the top; should be the fourth from the left). Those red characters should disappear, and the first few squares should now contain "00."
Now, in the English version, click the first square in the upper left in the main window, then from the Edit menu select "Block <n> chars...," and in the pop-up menu enter 100, then click OK. Then, in the toolbar at the top, click the "copy" icon (looks like two pieces of paper; sixth from the left).
Now, click the top blue bar of the window of the Japanese version to go back into that. At the very bottom of the program window, you'll see three boxes, "Adr. Hex:," "char. dec.:," and a third one that says either "overwrite" or "insert"--if it doesn't say "insert," then hit the "insert" key on your keyboard to change it to "insert." Then click on the first square in the top left of the main window and then click the "paste from clipboard" icon (looks like a clipboard; seventh from left). Save and quit.
6. Now, copy down the name of the English .IMG file, then delete it. Change the name of the Japanese .IMG file to the name of the English file you just deleted, and move it into the folder where the English file was.
7. Go back up two folder levels to the folder for the English updater, which should be something like C:\Dell\Drives\R101483. Click on setup.exe, and this time when you get to "DO YOU WANT TO UPDATE ROM" choose "Yes." Make sure your PDA is in its cradle with power and USP cable connected, follow the onscreen directions, and you're all set. Note that there'll be a couple of periods where the thing just sits there for a long time--this is normal. Unless the installer itself tells you to do something, don't touch your computer or PDA until it's all done. Interrupting the process could be very bad, indeed.
You're done. All menus and commands will also be in Japanese now, but if you're not fluent, you can compare what you see onscreen with the screenshots in your English language users' manual (all the menu items will be in the same places) to figure out whatever you need to figure out. Also, your newly Japanese Axim will work just fine with the English sync software on your computer, but it might NOT work with some English Pocket PC software (though it's worked with everything I've tried so far).
OK, so it worked. What did you just do? Dell allows you to update an Axim firmware only with a newer Axim firmware in the same language. When the updater starts, it checks to make sure that the new firmware is (1) newer than and (2) the same language as what's already on the Axim. That information is in the first 100 characters or so of the code from the firmware. So by copying the first 100 characters of the English ROM's code into the Japanese ROM, then replacing the English ROM with the altered Japanese ROM, we're creating a Japanese ROM that will tell the installer it's an English ROM.
In Step 2, for other languages or if the links above don't work, start at the Dell USA site, click Home and Home Office, Online Technical Support, Drivers and Downloads, enter Axim and X30 in the pulldown menus under Product and Model, on the next page enter Microsoft Pocket PC 2003 and the language you're looking for, System and Configuration Utilities, Dell Axim X30 System Update for Windows Mobile 2003 Second Edition, and then you're finally at the download page).
Potential workaround if your Axim is already running the same ROM version available on the Dell site. I would definitely not buy a machine with the same ROM version as the newest one online and count on this working--but if you've already got one, you might as well try it. After you've copied the first 100 characters from the English ROM to the Japanese in Step 5, in the right-hand part of the main window you'll see the version number of the ROM (something like "A06"). Change the number to something higher than what's already on your Axim; i.e., if your PDA is A06, then change the version number in the ROM to A07. This seems like it should work, but again I have no idea if it really will. I suspect that if it doesn't work, it simply wouldn't install, leaving your old system intact, or if it did install and didn't work, you could use the backup you saved to restore your English system. But I can't promise it won't turn your PDA into an expensive paperweight. I'd be confident enough to try it on my own equipment, but I can't take responsibility for yours. Remember, I'm not an expert, so you're doing this at your own risk.
Alternate way around the ROM version problem: try the instructions here, which also work for the X30. This whole procedure is actually easier but carries slightly more risk of bricking your device.