It’s not MIDI, but you can use a gate into one of Hermod’s CV inputs to control REC. I do this using a momentary footswitch into a Pulp Logic N.O. Sw 1U tile into Hermod. I’d imagine that you could use a MIDI-to-CV/Gate module to do something similar.
I suppose you could use hermod itself as that midi-to-cv/gate module. So on channel 1 (or any channel), use the gate output of that channel to trigger record by self patching it to the cv input.