This page offers a script, written by Stuart Bouyer, which will automatically turn the menues on your Zaurus to English.
WARNING: no warranty is expressed or implied here. Proceed at your own risk!
Download the conversion script
Here is my script for those brave souls that wish to have a near perfect conversion to English. The input methods and help files are still in Japanese, also have't bothered converting the address book.
The conversion has only been tested on C760, but should work for all three C7x0 models as the original instructions were for the C700.
If you wish to have MoviePlayer menus in English download the qmid files
If want the date shown in Japanese format rather than
2003Year7Month23Day then uncomment the line that reads
and comment out the one below it. Note this will leave you with some Japanese prompts - I'm still working on fixing this.
Hope this is helpful to somebody. Most information for creating this script was taken from mspencer.net.