Reverse Camera Fitting

[tc4332]

Hi All,
I am thinking about fitting a reversing camera that hopefully would work via the MMI when reverse is selected. SHMBO is not very happy with our A8 D3 'cos whenever she is in the car, driving or passenger, the parking aid fails (just a constant beep).
I have read quite a few posts that never actually end with a definite result. Some have suggested that it could be done by connecting a camera via one of the Aux video inputs on the analogue TV tuner, and then coding it with VCDS.
Has anyone managed to do this?
I do not fancy running a video cable from rear to front of car and using this http://www.xcarlink.co.uk/product.php?productid=58&cat=4&page=1 but again buying original Audi bits might well have to be the answer.
Any help would be greatly appreciated.
BTW, today I fitted a Roadhawk DC2 forward camera with 8GB SD card, 128GB SDX card on order. And also fitted the TyrePal TB99 TPS with five sensors. Both working nicely.