I did some more research tonight on the Vtec driver that I'm modding. It turns out the approach I was planning on taking won't work, but I think I have found a good compromise. I think I can do what I want with a single latched SIPO shift register, which should be an off-the-shelf part (I'm not holding my breath for Radio Shack).
I think I'm going to target at least one glitch mode, the PC keyboard interface (with sound interrupt if possible/stable?), a single [pair of?] touch point[s], power jack, power led, envelope led, and if I feel like doing some extra coding a store/repeat/loop mode. I really wish I had a pitch down on this thing, but I don't think I've found one yet....maybe that touch point near the xtal can be used, must look into it some more.
I'm rambling. Sleep time. Nite.