**** UPDATE 11/08/10
I dont know why I havent put this in earlier but you must have a look at Billys great thread on the alarms if you are having trouble with them.
Also if you find a thread useful please thank the person using the Thanks button
**** UPDATE 15/11/09
I have found out that not all receivers are located in the same place so you may have to look for yours. DragonLogic found his under the carpet as stated in the post below so keep your eye out
Also I didnt see this before but it is very helpful Pangsters 3G alarm Post and Ronnies 3G alarm post may be very useful to you too.
This is not a how-to more a, this-is-what-I-did. Below is a picture of the fob used.
Anyway you need to take your glove box out. It's quite simple, 8 cross head screws need to be removed. Two at the top in the air vent corners, two at the top of the box door, two just above the box hinges and two underneath the box where it meets the cardboard with your foot light in it.
Once you have the box out you should see something quite similar to the photo below. My alarm module (black) is tight in the corner and is difficult to access. My one is held on with just one screw. The arrow shows you where it is.
I don't know what the big silver module is but it's held on by two bolts and is very annoying. Even tho I loosened the silver module off it's still quite difficult to get the alarm module out. Below is the two bolts for the silver module.
Once you have gained access to the module you will see that the receiver has the wire aerial coming out of it. The photo below shows the receiver highlighted in red. You can take the receiver off of the module but only do this if you have a working fob as the alarm activates when the receiver is removed. I havent removed the receiver this time as I didnt need to but if you want to it just lifts straight up off the pins.
You will see a small hole possibly covered by a rubber gromet. Underneath this hole is a small switch. The switch should be in normal mode. When you flick it over (I just used a small allen key I had to hand) it will be in the coding mode. All you need to do is press the red button once of EACH fob that you want to work with the system then flick the switch back to normal mode.
Lets say you have a fob already working and your adding another. This means when the switch is in coding mode you will press the red button of your working fob. The alarm should activate but dont worry. Then press the red button of the second fob. Nothing will happen this time. Then flick the switch back to normal mode and your done.
i say done but I found the hardest part of all this is getting the module back in place and secured, it's a lot of fiddling. So before you do put the module back make sure you test all the fobs your trying to activate.
Hope that helps. This is how I got two extra fobs working so I now have 3 working fobs. I will not take any responsibility for your actions.