Cowboy,
I had thoughts of fitting a foot switch to a recent machine I had but I ended up scrapping it due to a bent arm. I should have kept it and tried to fit a switch anyway as I still want to fit a switch to my present machine. A circuit diagram for your machine would help (I couldn't get one from the makers of my scrap machine), but I reckon the foot switch would need to be placed in the wire that feeds power to the motor ?
Another point is the switch should be in some sort of shoe/covered block so that it cannot be accidently trod on while changing blades etc.
Don W