You should be able to disarm the system with the ignition key.
Open the passenger door the security light will blink quickly.
Put key in the ignition, the turn the ignition on within 15 seconds, but do not start the car. The security light should go out. The system is disarmed.
I got this from here: http://www.parksoffroad.com/tacomamods/alarminfo/alarminfo.htm