I have a 96 E39 540i with an aftermarket Pioneer head unit. I don't want to give up the head unit because it's awesome but it's annoying not being able to use the mid obc unit. I've seen a forum post from someone in america who wired his into the glovebox, but I don't really want to go messing around with the wiring myself.
If anyone is a pro at this kind of thing and could do it for me I'd be happy to pay. Am based in Surrey and don't mind travelling a bit.