(with navigation system and fold down seats)
I picked up my BMW CD changer from Steven Diamond ($375 + $15 shipping). It is part # 82-11-1-469-404 (Alpine, I-Bus). The changer comes with a cartridge, manuals (none for the E46) and 4 M4 screws. Steve also threw in 2 L-brackets (part # 65-12-8-370-925) free of charge, since he knew I was installing it in a navigation-equipped car (already have sidemount brackets).
These instructions were specific to (my) Y2K 323i Sedan with folding rearseat and navigation system.
I used a small 1/4" drive ratchet wrench with 6mm and 8mm sockets. A wide flatblade screwdriver is helpful to pry off the trunk liner rivets. Try to prepare your cd changer for installation in advance (also see BMW instructions).
Some of this differ from Dave Heckendorf's instructions (his was a '99, mine was a '00).
Using his instructions, modify these steps as follows:
1. Similar. You only need to remove two of the rivets fastening the left-rear trunk liner. Remove the LR tailight panel and unplug it. Remove the rivet by the tailight and the one in the upper middle of the trim panel. Now lift the panel up and swivel it out of the way.
The reason I didn't remove the third rivet is because it is nearly inaccessible (under the rearseat upright side cushion, accessible once you fold down the seat).
The rivet fasteners may be difficult to deal with. I snapped the head off one of them.
You're now looking at the existing bracket, the nav cdrom drive, etc. Now remove the storage tray above the cdrom drive. Remove 4 (8mm hex head) screws and set them aside. You'll need these later to mount the cd changer.
2. skip.
3. skip.
4. skip.
5. Do prepare your CD changer. Helps if you do this step ahead of time, before starting installation.
Note the cd changer L-brackets are mounted long leg of the L alongside the changer, and the short leg of the L sticking outwards. Use the 4 screws supplied with your cd changer (M4 screw with 6mm hex head) The short leg of the L are your mounting points onto the existing changer bracket.
6. Find the large bundle of harness behind the bracket along the fender inner wall. Unbundle them and you'll find the cd changer harness. Plug the harness in. Now for the AR types, bundle the harness back together with the wrapping material, and stick them back where you found them. Slide the cd changer into the bracket from the front (may have to apply some force and spread the bracket a bit). Bolt the changer in with those 4 screws you removed earlier.
7. Test your changer before putting everything back together!
8. Reassemble everything and you're done.
As you can see, it is very easy. Takes less than an hour from start to finish.