Nice.
Am working on a similar project myself, however am running a synaptic trackpad in absolute mode, and then I can get XYZ (z is pressure) for 3 MIDI CCs. Will probably create a library for my own use (I like to keep messy hardware code separate), would anybody be interested in it?
I am absolutely interested in your code, and which trackpad part number you used. I'm also working on an enhanced version of this project, but absolute mode would be best for what I am doing (and Z could add an interesting wrinkle...)