02 impala factory alarm

i installed a prostart lcd model r/s on a 02 impala using their obd11 by-pass kit gm-dt1000 which integrates passlock and locks and trunk.this unit is recommended for units with out factory alarm.i was told by the owner that he had the car checked an there was no factory alarm- wrong it did...Everything works fine however except when i unlock with the remote the content alarm will not disarm,i have to press unlock with factory remote.Do you think i will have success if i wire the disarm wire up to the bcm ?also i read somewhere that a double pulse will do the trick.I tried that a couple of times and it seemed to work ,but i'm not sure.i can go the long way and wire a by-pass for the passlock and do the locks and trunk separately using relays and 480 ohm resistor,but this kit seems to work ok
2nd question
Why do some wiring specs say to hook up the brown acc wire as acc ?as far as i know the brown wire should have no impact on remote starting as it only powers up wipers etc?
thanks ,bruce

The accs. wire IS needed, or the check engine light might stay on.

There is a factory disarm wire in the grey BCM connector at pin B3, lt. green. NEG(-) pulse will disarm

-------------