Stereo & Electronics - Alarm goes off without keyless entry

i have a 1999 trans am. i lost my keys and keyless entry and had to get the dealership to make me a new key. i no longer have keyless entry and have to use the key to unlock my car. here is my problem.....everytime i unlock my car my alarm goes off, if i dont get ignition turned over within about 3 seconds. so i am always unlocking my car and jumping in, so the alarm doesnt sound.
thanks for any help

Buy a replacement key fob (part number 16245100) and program it to match the car. In the meantime, you can program the alarm system off using the instructions in your owner's manual or posted here (http://www.ls1tech.com/forums/showpost.php?p=2965615&postcount=5).

Try locking the car with the manual slide button - believe that doesn't arm the alarm.

yea you have a certain amount of seconds before the alarm goes off after opening the door with the key