I have a MIDI Baby 3 here, rck.  I would think it’d be the same as the H9 setup: On Press – CC Toggle – Channel – Controller – send single value 127 – 0 counter.  I haven’t tried anything with the H90 yet.  There was a weird issue with mine (which DAD addressed immediately via return), where the MB3 got stuck in Host mode.

Let me see what I can come up with later on with the MB3 & H90.  (I’ve become obsessed with controlling the H90 with a Source Audio Reflex pedal).