I put one in for cryO2 in a buddy’s Jetta years ago. I ended up having to put it on the floor so when the peddle was all the way down it engaged the switch. There was a nub that stuck up from the floor to bumper the peddle I guess and that’s what I attached it to.
You could put it on the throttle body some how so when the flap is all the way open it touches the switch