Have you tried the old ibus interfaces that were used with the E38/E39?

Maybe they won't work because the required button is not present on the X3?

All you need to do is send an ibus command to switch video mode whilst not changing audio mode.

To do that you need a little microcontroller (like a PIC) that listens for the special button press, then sends the video switch command

Easy if you know how to build and program microcontrollers...

that my friend seems a little hard for me to do....if there is a plug and play solution id jump on it but think its out of my league

This is the advanced tv-in-motion cable that allows you to select alternative audio sources whilst viewing the TV. I forget the button press, I think it might be the <> button ....

http://www.toysinyourcar.com/acatalog/bmw_adv_tvim.html

Not sure however if this works on the X3 though ..... as already stated, its a slightly different set up.

i have a dietz module here ill give that a go, if that fails ill have to put up with the dvd in stereo