Hmm.. yes, now, when I think of it, I might throw away the idea of aftertouch.
I want to make a foot controller - you stomp on it and you get some kind of a drum sound (e.g. you play guitar, and stomp to get hihat, or cajon, or tambourine, or something similar to accompany your playing).
I wanted it to be able to play both sampled instruments and synthesized ones. And so I thought that I would need aftertouch to shape the sound. But now I realized that both samples and synthesizers do "attack/decay/sustain/release" thingy, and I have absolutely no need for aftertouch...
Damn.. Now it looks simple..