Hello.
In my case, I’m using a Yamaha DJX as a sound module to learn how to sequence with Zaquencer.
When using its GM Voice List, you just need to adjust MIDI CTRL (alpha) to [PrCh], so you can use MIDI CTRL (beta) for any other purposes, let’s say, for delaying.
BUT if you want another Panel Voice List (out of GM), you have to set MIDI CTRL (alpha) to [C32], and MIDI CTRL (beta) to [PrCh], and assign MIDI CTRL (alpha) to the LSB value in the list (and, of course, MIDI CTRL (beta) to the Program Change value in the same list).
Wish it is useful for anybody with the same doubts I had!!!