I purchased one of the changers on ebay, and the dealer rufused to install. It seemed simple enough after browsing the directions, which I now have lost! Basically I found 2 jacks that fit into the wiring behind panel in boot and connected them. There is still a small black wire that comes out of the changer with a silver tip, where does this plug into?? The changer seems to be working, except no sound, obviously this wire is important! Any help would be much appreciated!!

 

MSPin,
I was considering buying the same unit off E-bay. Found this install manual on BridgerMINI. Let me know how it goes and if you really need to rip out the seats, trim, etc.
CD Changer Install

 

MSpin
I bought the stock CD changer from BMW. It appears to be made by Alpine (detected by a reference on the single piece of paperwork, and Alpine on the CD Cart body). The stock unit however only has 2 connectors which mate with the harness. There is no extra lead coming out of it. Fitting is straightforward, providing the cabling is already in the car, you only need to remove one panel held in by clips to get the harness out. But you really need to cut the carpet on the boot floor to enable it to lift around the changer for access to tools, battery, etc.