Tried this on mine, works pretty good
Haven't tried any functions, but it's pretty much the same thing and it got this far so I assume they work.
Not sure if this is a bug or feature, but the trackball (pushed in) does what was last touched.. like, if I touch the down button, the trackball is mapped to down, and if I touch the OK button, it gets remapped to OK, etc
If I use another hardware button like vol up/down or power, it gets unmapped (to nothing)
If you're looking for new things to add, holding down on the up/down buttons to scroll quickly would be nice
(if that's possible)