ipod, nomad, etc input.
I recently found out on another forum that some companies make an interface to the CD changer input of various OEM headunits. My understanding of the interface is that it is a box with an input for your mp3 player and an output specifically designed to hook up to the cd changer input of your OEM headunit. So the headunit thinks it is seeing a CD changer, which is actually your mp3 player. Unfortunately I dont recall the names of the companies right now, but I remember visiting one of the websites, and they didn't support MB cars -yet, and definitely did not support the new optical digital CD changer inputs.
Steve