Try this instead the BCM hook up.
http://www.camaro6.com/forums/showthread.php?t=440254
I have it installed that way and never had any problems with it. Get you one of those converters and hook it up to the switched power in the overhead console. The converter hides in the console.
http://www.ebay.com/itm/Generic-12v-...1%26rkt%3D1%26