Location of door circuit

["Gersic, John" <JGERSIC@imf.org>]

 I have installed an aftermarket Stereo (a pioneer) which has a neat
alarm feature on it. What I was wondering is: is there a centeral
location/wire which I can tap which will let me know if a door is open?
I can connect to a particular door pin switch, but since they are all
wired to the factory alarm as well as the dome light, there must be a
relay which I can tap to determine the door status (maybe trunk/hood
too?) of the car..any ideas?