Hello everyone... noobie here (just got my PX-350 a couple of days ago). Like many folks here, I want to use it with my DAW (in my case, Cakewalk / Sonar) and have the DAW be able to select and use the non-GM sounds. After some research and experiments, I found the that key to getting the bank/patch select to work was to multiply the bank number in the manual by 128 (e.g., Bank 48 = Bank 6144, etc.). I've attached a a working .ins file for Cakewalk and Sonar users; other DAWs should have similar implementations.
Hopefully this can help others get started with this great instrument.
PX-350a.ins