Aftermarket backup camera tapped into stock display?

[Multibeemer]

I was wondering if it would be possible to tap the output wires from an aftermarket backup camera into the terminals that activate the video display on the stock nav display screen, allowing me to see what the camera sees on the stock display, and avoiding having to mount an extra display on the dash. It would be a very cool upgrade - has anyone ever thought of this, and if so, any idea which connectors I'd connect the camera's wires to? Is it even possible to have the output from an external device like a camera "override" what's normally displayed on the screen? Thanks.