As the memory is base in the board it harnesses all of the control e.i. open/close function which basically means turn on DVD player, mute sound <> Nav Voice etc.....You will pretty much have to build a new unit, which gets back into the ridiculous.
Its good to dream though, but they are right why not just get an external DVD drive to run the dvd functions it will cost you less FAR less, LOL instead of playing McGyver (if it aint broke dont try to fix it)