Not sure what the bump is for, but in case it's about how I did it...

I left the BMW socket alone and made my own connector lead with adapters and stuff. If I was going to install it permanently I would make a special lead that directly matched (i.e. no adapters used) the iPod output to the BMW input. Just follow the pin configuration I described above.

I cannot now remember which output I used from the iPod - it was just a test to establish the BMW socket configuration, but IIRC you can only get composite video from the dock connector on the base of later iPods, whereas earlier devices output CV at both connectors. That's a bit speculative as I don't have an early iPod to confirm.

For the audio, you need the iPod to output MONO or you'll just get one of the channels and it'll sound terrible.

There are ways to use this video input with the Stereo AUX input I believe, but I've not tried that.