For iLiad with European firmware, the writing pad has an option of "簡體中文"（simplified Chinese） but it's grayed out. There is a way to enable this option.
Here is the steps:
1. Get a firmware image or iLiad with Chinese firmware.
2. Mount the firmware image on your Linux by using "mount -r -o loop".
3. copy everything in /usr/lib/gconv and /usr/share/ereaderim/res/zh_CN to your iLiad. It's done.
/usr/share/ereaderim/res/zh_CN is about 4MB. Instead of putting it in rootfs, I put it in /mnt/free and make a symbolic link to /usr/share/ereaderim/res/zh_CN.
I guess iRex uses VisionObjects's technology as the base of iLiad's handwriting function. Maybe I can add more supported languages by copying something from MyScripts Notes.