Overriding needing park to watch dvd

Ihave no probs porting my own rgb into a factory head,but I would like to know what anyone knows about overriding the gm's pesky need to be in park to watch a dvd?!?
I will continue to do what i do,any one of my customers has no problem w/another 200 bucks for another dvd,The backup cams using the fact screen will need the rgb-in anyway..
but if i can avoid it why not?I am thinking of an endless loop digital signal to the radio,and just putting a peripheral databus/bose/whatever(I guess a chime mod is enough huh?) to take over the ack's for the pcm. Any ideas?
I just figure this must exist somewhere..

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'Stereo' Mike
The Audio CARtist,LLC
9600 Balt. Ave.
College Park,MD 20740
301-474-6260

Typically automotive dvd players and monitors have to be hooked up to the parking brake, and have the brake engaged to opperate. The wire from the harness that says "Parking Brake", you just need to hook it up to a ground, when it is grounded you will be able to watch a dvd anytime.

Not an aftermarket,I modify the factory headunits to allow me to run any video input into the factory screen,some of the gm units allow watching a dvd in park..now there is more than what is on the aftermarket telling the factory radio that it isin park,it is done through databus information..I'm figuring i can do some kind of override of this situation..I am wondering if i can put enough data(well,the right data) into the factory unit to turn it on ,but make it think its in park..now to disconnect it from the cars,i need a pac,or similar adaptor to keep the car 'happy',the factory unit has all kinds of unrelated info in it,some of them have airbag info in them!(i think it has to do with onstar..whenthe airbag goes off,it calls onstar.no matter what..).
i am figuring 'recording' a datastream,putting it on and endless loop,telling the radio to 1)come on(no sw power),2)the car is in park..i need someone that knows about the specifics of the databus 'language',how much has to be ack'ed from the radio? will a oneway comm from a 'recording' do what needs to be done? i can just send the info for ..lets say less than 100 bucks,but once i need to reply to stuff,i need a processor!lets start that at 1000 bucks!this wouldnt be worth it! a top-of-the-line dvd,and all the parts i need(not to mention 5-8 hrs of labor)cost me less than 600 bucks!!!!,but if i can do the 'override' for a similar amount of money,most of the people i deal with would rather not have to put a dvd anywhere other than the factory nav unit..a much cleaner install..so if anyone can speak GM databus,not absolutely fluently,but knows enough,i can build it,and do board-level mods..after all,i have to do this to use it for backup cams,or a dvd as i am doing now..i am allways looking for perfection for my customers! like overheads..I always do a pullup on the brackets i use for the overhead monitors,sunroof or not! this is one of the few businesses i ca n be so extream in my work,and get paid accordingly..I LOVE IT!!!!!

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'Stereo' Mike
The Audio CARtist,LLC
9600 Balt. Ave.
College Park,MD 20740
301-474-6260

Now that i think about it,interactivity is needed,for vehicle speed for asl,and calibration of navi(like in a tunnel,with no gps ant signal)these are the types of things i need to speak with someone about..in a month or so,i will have the time,but not the money for equipment to interpret the databus!..you guys get the idea..
Thanks in advance,even for the thought!!!!!

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'Stereo' Mike
The Audio CARtist,LLC
9600 Balt. Ave.
College Park,MD 20740
301-474-6260