Go to montgomery road
there they can install a pre/DVD player in the empty space below your setup
like this
It will give an output in your TV section of Original DVD player/MFD.
When you switch to TV, all you get is static, but after installation, you will get this when playing mp3 or videos
i've been using this for a while now. Works like charm and now anything can be played directly from USB.
P.S get a Good quality PRE/DVD player and mechanic should do good connections else sound quality will suffer
P.s.s try running the display when parking brake is NOT engaged, as display will get off when Parking brake is off, The Mechanic will also know a bypass around it, will take a minute or so