you dont have to buy the twenty or thrity dollar plug if you dont want to. Just run to wally world and pick up a short phone cord, use the two middle wires for power and ground. If you plug it in backwards, just turn the wires around. It wont hurt the detector if you plug it in backwards.
Other than that, just a place to mount it.
if you need anything else just let me know. Ive done about a dozen of them and have faced just about every problem you could.
Josh