The links below are for the Video Entertainment System retrofit I had done on my ML.  They include the WIS and Owner's Manual.  Other than eBay the VES is no longer sold by Mercedes or anywhere else I have been able to find.  If you locate something let me know and I will post it here.  I also upgraded my VES with the OEM DVD player made by Rosen, but as above, they may be very hard to find.