Buy an Eijiro password, then download and decompress the files (the files are freely downloadable, but you need the password to decompress them).
One important note: Eijiro is produced by and for professional translators. They're a non-profit making a fantastic resource available dirt cheap--they're essentially providing a public service and charging just enough to cover their costs. It'd be a crime (literally) to steal from them and a shame if they were no longer able to keep updating the file or no longer able to make it available at all. Please do not share Eijiro online through file sharing (P2P) services. Besides being sleazy, it's dangerous. They can trace the file through the password used to decode it--their lawyers contacted me when someone I'd bought it for posted it on a P2P site (obviously it"s down now). Fortunately, I was able to connect them to the guilty party so they decided not to sue me. Your copy of Eijiro will be registered in your name with your contact information--if you share it with the world at large, they will be coming after you.
Once you've got all your decompressed Eijiro files in a folder somewhere on your computer, download and install a program called Personal Dictionary (Windows -- Mac). The following instructions are for the Windows version, but I think the Mac version should work similarly. From the Tools Menu, choose 辞書の変換. In the window that pops up, choose the following options:
Click 参照 under the left box to browse to the file you want to EIJI-XXX.DIC or WAEI-XXX.DIC; click 参照 under the right box to choose where to save the resulting file and what to call it. There are no other options to set. Click OK, and it will create a specially formatted text file.
Personal Dictionary is also a pretty good dictionary reader program. If you want to use Eijiro for your desktop or notebook computer, move all the Eijiro files ending in ".DIC" and the "TEXT" folder into the Personal Dictionary folder in C:\Program Files (or wherever you installed Personal Dictionary to).
Here's a step you might have to skip. The file you've downloaded will be in the order it's in in the original PDIC file. Capital letters are alphabetized BEFORE lower case. The problem is that, unlike in PDIC, searches in EPWING are not case sensitive. Enter "cat" and you have to wade through every single word or phrase that begins with "CAT" or "Cat" before you get to plain old "cat"--you have to do quite a bit of scrolling before you get to what you're looking for. The solution is to completely re-order the Eijiro 1行テキスト形式 text file you just made (and that of Waeiji, for good measure, as there are a few English-first entries there, too) before converting it to EPWING. How do you take 1.8 million entries and put them in case-insensitive alphabetical order? If you've already spent $150 for a program called PowerGREP and have 2GB or more of RAM to play with, it's easy (though it'll tie up your computer for quite a while). And if you've got rad PERL skills or the equivalent, I'm sure you can come up with something. Otherwise, you've got to live with some occasional inconvenience in your search results. However, since I have laid out the $$$ for PowerGREP and RAM, the version of Eijiro you'd get if you bought it through me, either as a download or already installed to a memory card, wouldn't have this problem.
Next, download and install EBStudio, if you haven't already--you'll need to buy a registration code to use the good indexing options (sorry, I don't know what to use for the Mac). Open EBSTudio and from the ファイル(F) menu in the main window, choose the first option 新規作成(N) ("Make a new book"); or click on the first icon in the taskbar, the blank sheet of paper. The Output Dictionary window will pop up:
1. What you want to call your dictionary
2. Desired subfolder name (up to 8 alphanumeric characters, not important what you put).
3. Type of dictionary. 英和辞典 for EIJIRO; 和英辞典 for WAEIJIRO.
4. Copyright information file (in HTML format). LEAVE THIS BLANK
5. Index term/keyword definition file. LEAVE THIS BLANK.
6. Gaiji information. . LEAVE THIS BLANK.
Click OK, and then the 入力ファイルの登録 (Input File) window pops up:
1. Name of input file (the one you created with Personal Dictionary, above). Ellipsis button to browse for file.
2. The name you want to appear in the menu of your dictionary reader software menu (anything is OK).
3. Format of the input file: PDIC １行テキスト(1)
Click OK, and now you're back to the main window:
1. Leave this alone.
2.入力ファイル Input file. You entered this already in Input File window above, so just leave it alone now.
3. Folder into which you originally decompressed the Eijiro files. Use the ellipsis (3 dots) button to the right to browse to the location.
4-7. Leave these blank.
8. Output path. Make an empty folder somewhere--this is where the EPWING dictionary will be created.
9. Format of the the book/dictionary you're trying to create. Choose JIS-X4081(EPWING).
10. Indeces to create. When you search for a term, the search engine searches the indeces rather than the entire file (this is why a huge dictionary can be searched almost instantly--actually searching the dictionary itself would take much longer). You must create an index for each type of search you want to allow. Check the first four:
If you haven't registered EBStudio, you can only create the first two types of search, for terms beginning with the search term. However, it would also be useful to be able to search for words ending with a particular character or characters--probably worth the 1000 yen it costs to register the program. The more types of search you enable, the more flexible the final product will be, but also the index file will take up more space on your memory card.
Now, set the options. Pull down the オプション(O) menu and choose the only thing there (or just click on the crossed-hammer-and-wrench icon in the taskbar) to pop-up the Option menu, below. First, click on the 本字 tab.
Next, click the INDEX tab.
Next, click the マルチメディア tab.
Next click the 英辞郎 (Eijiro) tab.
Finally, click the 作業領域 (Buffer) tab.
Use the values shown in the image. These all tell the program how much memory to set aside when it starts processing. If you set the values too low, you get an error message for not allowing as much as Eijiro and Waeiji require. If too high, you get an error message telling you that your computer doesn't have enough memory.
Now you can click OK. This will save all the options you've set and take you back to the main window.
Click the red exclamation point icon in the main window taskbar to start building your EPWING file. You can follow the status in the box in the bottom of the window; when it says "カタログを作成しました。処理を完了しました," it's done.
The final product is the folder you entered in line 8 of the main window. Copy the entire folder to wherever you want to use it. It contains a file called "CATALOGS" and a subfolder (whose name you chose in another step) containing two subfolders, GAIJI and DATA, which in turn contain the main data files. If you didn't use any gaiji, the GAIJI folder will be empty, but don't delete it.
Now you're done.