The old - made free - Fitaly for PalmOS through 4.x, on WristPDA gives me a "Fatal Exception" when I try to invoke it by a diagonal stroke and a tap on "abc" - whether "registered" or not (I think), and whether run through Hackmaster or on its own.
The VirtualKB - for the same OS - works on WristPDA and is programmable, but I think that a useable approximation of Fitaly on the tiny WristPDA would need to have fewer and larger buttons than normal - perhaps only the letters and very basic punctuation to fill the display width. Then an alternate numeric keyboard can hold the special options. Something like that.