Does anyone know if the OEM nav screen will accept input from a backup camera and how diffiucult the install would be?

 

i see that you are new here, and the answer is yes. There is a unit called TVNav2Go that is being sold in the blackmarket/groupbuys section. This unit will allow you to put in any video sgnal into the navi screen via stock wires. The back-up camera would plug into that unit and whenever the car is shifted into reverse, it shall change the input to the backup camera. I myself have not installed the unit, but many other members have installed it.

 

Like csmeance said, Yes it's possible to install a backup camera and view the image via the Nav Screen. I have it done in my car and it was very simple to do. All you need is the TVNav2Go unit (aka Dom's Unit) and a camera.
The installation is very simple. The hardest part is removing the actual interior panels, where to mount the unit and knowing which wires to tap into for the reverse trigger (green wire @ the reverse light socket). Everything else is just plug and play (if you buy the plug-and-play harness from Dom). Another note would be to get the power source from the accessories power socket in the center/under amrest compartment (tap the white wire @ the socket). This is a switched power source for a clean install. Others actually use an add-a-circuit plug at the fuse box (Driver's side kick panel) at fuse number # 32. I personally don't like that method. Another suggestion would be to add a delay or pop eliminator (can be purchased @ www.autosound2000.com model N-66 or N-66A) between the reverse light wire and the reverse trigger wire on the TVNav2Go, so that the screen doesn't switch to reverse view (camera view) everytime you try to shift directly to park.