I don't know how to handle wiktionary.org, it's an online Wiki, not a downloadable dictionary. But you can use one of the free dictionaries from www.freelang.net
. Here are the instructions to convert them to the PocketBook format. I have used this method successfully for an English-German dictionary.
1. Get a dictionary from www.freelang.net
and install it somewhere. This will give you one or two files with extension .wb.
2. Get the Tool freelang2txt: http://3ppc.net/Users/SiD/freelang2txt.zip
3. Unpack it to the same directory as the dictionaries, then run
freelang2txt English-German.wb English-German.txt
(you need to change the names depending on the used dictionary)
4. Get the PocketBook converter: http://pocketbook.com.ua/file/DictionaryConverter.zip
5. Unpack it with all subdirs to the same directory as the dictionaries
converter.exe English_German.txt eng
The "eng" subdir contains instructions on how to handle things like singular/plural, and the keyboard layout for the PocketBook keyboard. You will need to edit it if the source language is different from English.