Ive just put a single din in mine, couldn't be bothered with the hassle of importing in a vw unit and messing with the can gateway.
I bought the single din conversion fascia from vw, fakra aerial adapter and the harness adapter.
I had to add an ignition fed 12 volts source to mine as there wasn't one there, this was easily picked up from the fusebox with a piggy back style fuse.