You can use any number of controllers, such as the Love controllers linked above and used in the original brutus build, or Ranco ETC-11000's, or Johnson A-419's, or the e-bay STC-1000 aquarium controllers. There are multiple options for probe placement. I have my temp probes installed at the MLT return, and in a thermowell in the side of my HLT. As far as connecting, you'll need to run power to the controller, one leg of power to the valve, and the other leg of power through the controller to get switched and then out to the valve. Just think of the controller as a switch that turns power on and off. If your valves run on a different voltage than the controller (12V, 24V etc.), you'll also need to use a transformer.