I just bought a new Escort Passport 8500 X50 and hardwired it into my 2002 Monte Carlo LS. Originally my plan was to wire it into the DIC (little display for gas mileage/compass/etc. above the rear view mirror) but this proved impossible because it would require removing the entire ceiling. After some fooling around with a multimeter I found that 5 wires go to the rear view mirror via a molex connector, but only three of them are actually used since my mirror has no OnStar or automatic dimming. Here's a pinout of the wiring for the RVM:
1:Brown - (Not Used) Constant 12v when car is OFF
2:Black - Constant 12v
3:Green - (Not Used, wired to my radar detector) Constant 12v except when in Reverse OR when the headlights are on as a result of pressing one of the buttons on the Keyfob remote (With the ignition ON or OFF)
6:White - 12v for interior light override (from light control knob/alarm/keyfob/etc.)
7:Blue/White - Ground
NOTE: Pins 2 and 3 will automatically turn off 10 minutes after the car is turned off if enough current is being drawn. In my experience the radar detector DID NOT trip this but leaving the map light on did (as it is designed).
Anyways I simply stripped a piece of telephone cable I had lying around the house and used solder to wire it directly into the back of the molex connector. Being that it is telephone wire, the connection is kinda shaky (the radar will shut off if you touch the wires) but I think it's mostly a grounding issue. In the future I will likely try to insulate it with more electrical tape. Here are some pictures!
Side view of the wiring and the connector
Close-up of the molex connector
Side view from passenger side
Close-up of detector from driver side
Entire dashboard view from driver side
View from outside (RD is barely visible in direct sunlight due to tinting)