I tried this myself. The delay option on the instant command is not long enough when set at maximum to allow the M100 to differentiate between commands. You can of course get the Helix to send an instant command on preset change or snapshot change.
You will also need some kind of isolated relay to go between the Helix and the X100 because the X100 ground is -6vdc and the Helix is 0vdc, meaning that the sleeve connection between them shorts the -6vdc and eliminates the potential difference when the EXT AMP switch is closed. I had to current limit the circuit with a 10k resistor while using my pedalboard's 9vdc to change potential enough for the X100 to perceive that as a button press.
https://photos.app.goo.gl/QvMTqx3x7r65TpVu8
