Disable the hood switch. There is a switch under the hood that is tripped when the hood is up and the alarm will never do anything if the hood is up. It thinks the car is disabled and won't work. If you wire that switch that is right by the hood latch to think that the hood is always up, it will never arm or do anything.
its actually pretty easy. if you want to completely uninstall it...
you have a couple of options here. if the door sensor is NOT fried:
close the door with it unlocked
put your key in the door, then lock it.
wait a minute or so, then unlock it.
when you cycle locking/unlocking the door like this, it is supposed to reset the alarm.
or you could go under the hood of the car, find the two wires that go to the hood sensor (so if someone pops your hood, the alarm sounds) cut them, and splice them together. this will make the alarm think that there is a door open, in which case the alarm cannot be armed.
this is the route i took:
go under the dash on the driver's side. attached to the steering column way up under the dash near the firewall is the alarm computer.