Ok, after a lot of playing around I've figured it out. There will be "official" support in PBC 2.0 firmware, but for now, here's how it gets done.
First thing, you need to program your H9 (or Timeline) with CC numbers for the looper functions. Why they don't assign some default numbers is beyond me. With nothing to go on, I will assign these numbers in the PBC and GT:
Record: CC37
Play: CC38
Stop: CC39
Empty: CC40
Reverse: CC41
Octave: CC42
Now on the PBC, edit the Record, Play and Stop buttons as follows:
- Set the button to send a CC Toggle action with the appropriate CC number from the list above (off:0, on:127)
- Turn all of the button setting checkboxes off (Tempo, Momentary, IA Link, etc.)
- Set Group to 1 (or to the first unused group number if you are using group 1 elsewhere)
It will work better if you put the Stop button to the left, then the Record and Play buttons to the right. This is just due to how groups work - the leftmost button is the one that defaults to on.
Edit the Empty, Reverse and Octave buttons as follows:
- Set the button to send a CC Toggle action with the appropriate CC number from the list above (off:0, on:127)
- Turn all of the button setting checkboxes off (Tempo, Momentary, IA Link, etc.)
- Set Group to None