If it's anything like the 99-00 W202's, I think all that is involved is pulling out the trunk liner on the right side, looking for the power and fiber optic wiring (should be attached together on the right side of the trunk), installing the bracket in the pre-drilled holes, and plugging everything in. May want to re-install the trunk liner before you actually install the changer unit, depending on the layout of the unit.

You MAY need to have the radio programmed to recognize the changer, but I would install the hardware and see if it starts up first.

Anthony