1999 Cavalier alarm

i am trying to install a car alarm in a 1999 Chev Cavalier z24 just a ProGuard System3 ALRAM not remote starter, anyways i can't find seem to find a wire that produces power when the door opens, i checked the dome light and it produces negative when opened and positive when closed, could someone that has done this car before tell me the wire color and location that they used, also i need a hand with the horn siren. Parking Lights   what wire produces - when the parking light swich is in on position.

Heres what i have

pin 5 - GREY- Horn/Siren out(this wire will output + or -, see pin #4 input

pin 4 - Grey/Blue Horn/Siren in(Connect to ground or + 12 volts, for polarity control on pin #5

i have a wire coming from the horn that when touched to a ground will honk the horn and i have the red and black wire coming from the siren , can some please tell me how to hook these up properly, i'm havin a hell of a time, i've installed many alarms , but this chevy seems like gm did everything possible to make it a pain in the a$$ to install anything???

i already have all thoughs hooked up but still not sure about something. Like i HAVE the diahram listed on the site but still don't know how this goes. So how exactly do these go

pin 5 - GREY- Horn/Siren out(this wire will output + or -, see pin #4 input

pin 4 - Grey/Blue Horn/Siren in(Connect to ground or + 12 volts, for polarity control on pin #5

i know it tells me right there but i can't understand what i do, do i hook up the + from pin 4 and the siren to a COSTANT power then grey - to horn and were do i put siren negative like hoes that work.