I had previously swapped the pre-2010 RNS-E in my 2006 B7 RS4 to a 2010 RNS-E (an A3 one with the faceplate swapped) so that I could play SDHC cards instead of SD cards.
Today I finally fitted the 8P0 057 785 AMI that had been in my study for over a year, so I now have a 250GB hard drive with all my music sitting in the glovebox.
It took about 2 hours (I had previously swapped the audio leads into a 32-pin AV connector that the RNS-E uses) to route the cable alongside the CD changer cable (so I could easily swap back if needed) and solder the 4 connections (+12V, GND, CAN Lo & CAN Hi). A couple of minutes coding from 309753 to 309721 to enable the AMI and disable the CD changer, and I had a working AMI.
AMI unit in glovebox:
Hard drive appearing on MEDIA menu:
Album playing from hard drive: