B7 is 90% different than the North American Passat not sure if that applies to the handle/camera set up, but I think the RNS510 is nearly identical.
It was easy for me to wire a camera in our 2012 NMS with RNS315, run a wire back from the head unit to the trunk by the drivers side foot well up the trunk arm(this is going to be different than the B7, as they prob have the fancy low profile hinges, think MK5, rather than the cheap bulky swing arms of the NMS) tap into a reverse light wire, then swap out the OEM trunk handle with the new camera handle. Then code the RNS to sense the camera when placed in reverse.
There are some DIYs out there for the NMS, should work but it'll be slightly different.