Faster and Easier Text Entry for Tablet PCs

This is what I use on my Palm. Takes up very little screen real estate
-- there are only 9 boxes, and they translate to every letter of the
alphabet using various clicks and swipes. Steep learning curve, steep
price, and I'm not sure if it would be easy for a mouse emulator. But
it might be what you're looking for.

http://www.exideas.com/ME/Pressfolder/PressReleaseDec2-2003.html