Jackaroo

I'm running a speedyefi ecu which has a secondary spark and fuel table in tunerstudio that you can switch on and off based on board input pins.
My question is how do I wire a simple on/off switch to send a signal to activate this input pin, making the tables switch?
For example where do I solder the wire to, how should the wiring be layed out, how should the ground be set up, etc. Thanks!