Video Switcher Mod

I'm working on a light/video setup for my friends' band. One component is a video switcher I want to trigger by the snare drum; contact mic into one of these amplifiers into the select button on the switcher below. My question is about the easiest way to modify or replace the switch so that it operates on the signal from the amp instead of the mechanical pushbutton. I don't expect that to be simple... another option is to wire up a small motor that simply pushes the button from the outside.
The other component of the project, anyway, involves more contact mics to amps to light organs, to visualize the drums. That part is a little less worrisome, although after investing in a lot of parts I made the mistake of seeing what the same money could've gotten me at guitar center... oh, man...
This is my first post. Thanks a lot for any and all ideas!

Picture of Video Switcher Mod