i have a 03 s430, i heard theres a module that you can use to convert you navigation to show regular dvd's. ive been looking cant seem to find anything.

 

try tvandnav2go.com. I have a 2000 s500 and just completed the install. They will re-program the command unit so the blank button on top controls the tv. I mounted the separate DVD player in the glove box. Worked out well. Good luck