Yeah, my car is not pre-wired either because its Euro spec not US spec, so a little more work. The worst worry about the work for me is actually the visible stuff, drilling any holes and removing things like the carpet and glove box, as I've never done much car work before. But running cables, soldering and electronics I'm okay with so thats fine.
Where did you see BMWNav photos? BimmerTech & BimmerNav both claim OEM parts on their websites I believe. Let me know how you go with yours, some pics would really help me.
I wonder if we can get the EBAs for the Bluetooth Retrofit kit?
BTW, this is the kit you want I think:
and maybe this: