Followed the directions here to tap into the existing wiring behind the light. I have a Beltronics 955:
http://www.beltronics.com/store/vector-955.html and got the direct wire kit:
http://www.beltronics.com/store/dire...tplug-red.html.
Snipped the + and - off the ends of the direct wire kit, and used vampire taps to connect them to the corresponding + and - on the factory harness.
The direct wire kit comes with an inline fuse, make SURE if you wire your detector you put a fuse inline on the + lead to avoid having to buy a new detector if you screw up the wiring.
I've already replaced the factory deck with a Pioneer P4400BH, so I wasn't using the factory bluetooth mic any more. Decided that I'd get out the dremmel tool and a zip tie to mount the direct wire kit onto the faceplate of the factory bluetooth mic.
Here's some photos:
