No you can't just use the existing switches, well that's the theory anyway as it already carries current that could effect either device (MPU or Trigger).

This was my main concern when I first started looking into it and as you will see the Ghostbusters dude used secondary switches..

Shame I know but looking at what GB dude did and some creative thinking I am sure we could come up with some good results. I am old school but these optical switches might also be useful (the ones found in more modern machines)

Something to think about anyhow, I will be interested to see what you come up with and I will share what I do with it as well.

Cheers: Brettski... :)