Originally Posted by HPIA4v2

Have you looked here:
http://www.xoutpost.com/bmw-sav-foru...tml#post672693

Not sure if 4.8 has the same LCM at the front passenger foot area.

But it's one of the cleanest, else in the steering column area, there is yelow/brown stripe wire that is ACC (accessories pos 1/2 on) you can splice; but I can only suggest test it using DMM to make sure.
GL.