First, make sure you have your H90 receiving and MIDI controller transmitting channels set…
You can set the H90 receive channel by going to “System” and selecting the “Settings” tab. Lower left you will find the MIDI mapping & sync stuff.
Then, while in the System page, select “External Control” tab… There you’ll see a listing of all H90 mappable parameters.
Find “P Act/Byp (M)” … Set the MIDI CC# in the MIDI CC Field (I use 0 for putting the H90 in full bypass, CC#1 for “A Act/Byp” to bypass of Alg A and CC#2 for CC#1 for “B Act/Byp” of Alg B) … Now you can set your controller transmit channel and CC’s appropriately.