Given the example of the temp switch I linked to, you would wire your compressor to a plug that would plug into the switch, then plug the switch into the wall. You would then need to find a safe place to penetrate the wall of the kegerator to install the capillary bulb. The capillary bulb is where the sensing will be. As the gas expands and contracts in the bulb, it makes and breaks the switch. Shoot me an e-mail if you want
psychodad@cox.net I can send you links if you want that may better explain.