Does anyone know to add an additional keyless entry for my 1997 Saturn SL1?

Get one from your dealer

Well I just did this tonight and it worked :D I bought a second key fob on ebay for our 1999 SL2. I found this answer on someones elses forum Saturnfans.com/forums (thanks to spencerb) I saved a lot of money.

Here's how to program a new remote: Jumper pins 4 and 8 on the OBDII connector by the driver's left knee (I used a paper clip; may SURE you jumper the correct pins or very bad things could happen). You do not need the key in the ignition. Place the paper clip in the 4 and 8 jumper pins. You should hear a horn chirp, then hold the lock and unlock buttons on the fob until the horn honks (should be about 15 sec.), now hold the lock and unlock buttons on the second or third transmitter. The trasmitters are now programmed. Now pull out the paper clip and you should be good to go. This is valid for '97-99 S series with the Saturn Security System (I think).

All existing remotes will no longer work if not programmed with the others.

If you do buy a remote from ebay, made sure all the numbers match. Some remotes look exactly alike but they are not the same.

Could you tell me what the numbers are on back of the remote. I have a 1999 sl2 but no remote to compare the numbers to. I plan on getting used one but can't without numbers.

we have a 1999 Saturn SL2

the numbers on the back are as follows

GM 16245100-29
CANADA: 218101368
MODEL/FCCID:AB01502T

Hope this works for you. We only had one fab that came with the car when my wife bought it and it has the same numbers on it.

Good luck any other questions feel free to ask.