hey ed thanks heres the info you wanted:

A) yes i do have navi
B) i purchased the kit the Tom suggested from EAS(look at post #5), they have both kits with and without Navi, the harness is right there behind the Unit it clips right in.
C) i check out post number 24 in the STEREO section on the home page, Installing the AUX Input on an X5 - X5world

D) my X5 is a 2006 3.0i without DSP and it has Navi.

i actually used my key and my fingers to pop off the trim around the Navi. it comes right off. start at the bottom and work you way around, it will pop right off. its really simple, on my X the top screws are in the coner not in the middle like in the picture, i guess they changed it, and its T10 screws. and run the wires up from the glove compartment first dont clip it in and try running it down its harder that way. you can just grab it with your other hand if you push it up throught the glove compartment. sliding it down it will just go where ever it wants to go. and when you make the holes for the faceplace screws make very little holes and force the screws in so its nice and tight and wont come loose. good luck let me know if you need any more info.