I've got one on my truck. The previous owner had it installed by the dealership I believe. I don't really even know if it works since I store my truck in the winter, I've never had to use it. Anyway here are some pictures I just took.
This is where the plug is.
This is where the cord comes through around the top driver side of the radiator.
The cords then goes down to the freeze plug thats hiding down there some where. About the time that the cord goes out of view in this picture it starts getting wraped in some sort of heat reflective material.
That's about all I know about it since I wasn't the one who installed it. HTH