Here is the text from the cd changer installation procedure where the link doesn’t work anymore:
SLK CD Changer Installation
This page documents the installation of a CD changer in the SLK
By Rafael Tamayo. E-mail:firstname.lastname@example.org
I bought the MB OEM (I believe it is made by Alpine) changer for about $450 from Auto Class in Miami, FL.
There I spoke with Gaston, who was very friendly and ready to lend a hand. Go to: www.autoclass.net
The installation is pretty simple and anyone with some mechanical experience
should be able to do the whole thing in less than one hour.
Step 1: Locate the factory wiring. The cables are located behind the access panel in the passenger side of the trunk.
There are three orange fiber-optic cables. Two of the cables (labeled HU-OUT and TEL-IN) lead to one connector head,
and the third cable (labeled HU-IN) lead to another connector head. There is also a black power cable.
All cables are tie-wrapped and must be untied for the installation. (Finding the cables was the hardest part of the installation.)
Step 2: With a small flat-head screwdriver, carefully, unclip the connector heads for the fiber-optic cables.
Recombine the cables so that the HU-IN and HU-OUT are in the same connector head.
Step 3: Pull out the head unit from the dash. A special tool is normally required for this, but I was able to do it using a Swiss Army knife.
Insert a small blade or file in the slits located in the lower corners of the unit, unclip one side first and then the other one.
Step 4: There are four orange fiber-optic cables leading to two connector heads.
Again carefully unclip the connector heads for the fiber-optic cables.
Step 5: Recombine the cables so that the CDC-IN and CDC-OUT are in the same connector head.
Hook up this connector to the head unit. Replace the head unit in the dash.
Step 6: Go back to the trunk and hook up the fiber-optic and power connectors the CD-Changer unit.
Cut a small notch in the access panel lidfor the wires to come out of, and replace the lid.
Step 7: Secure the changer into place. I don’t have the bracket but I used Velcro straps and it worked fine.
The old installation link does not work anymore. Here is a head unit removal link.