Wiring Avalanche tailgate alarm?

2003 chevy avalanche factory alarm.

I am trying to arm my tailgate and cargo boxes which are on self grounding pin switches and have a common ground wire which I have tapped into at the dash control switch. Cargo lights come on when the tailgate or a box cover is opened. The same lights are also manually controlled with the dash switch. I am trying to get the activated ground wire at the dash switch tied into the factory alarm. 

Could I put it on one of the door triggers at the BCM box?

Are the door trigger wires negative or positive? 

If this is possible and it was diode isolated, I beleive it would stop the cargo lights from coming on when the door was opened, but interior cab lights would come on when a cargo pin switch was activated. Please help if you know of a better way to wire into alarm or if my wiring into door trigger is going to fry something.

I have no hood pin switch.

The two boxes and tailgate have a self grounding pin switch. The pin switches are connected into the cargo light wiring on the ground wire. The lights have two wires (+ &-). The negative wire to the lights goes to the manual switch located on the dash. The switch grounds the wire to turn on the lights. The pin switches on the tailgate and boxes mimic this. Everything is factory except I have tapped into the negative feed with the pin switches. 

Convert polarity (to positive), diode isolate and connect into the gray/black door trigger at bcm. Right?

Thanks for the help.

Used the rear door trigger at the bcm with diode. System works. Would like to install a relay to block the cabin lights from coming on when the tailgate or saddle bag is opened. Is there a wire thats constant +or- only when the alarm is activated? Would like to use this wire to control a relay.