If it's still got the original fitment, it'll be a Scorpion 918U. As to new fobs, you're probably out of luck as the system isn't supported anymore.
The control unit will probably be behind the main instrument cluster. Easy enough to check for it : Lower the steering wheel to as low as it can get, undo the two allen screws holding the instruments in and then ease the instruments out. If there's a black box with 'Scorpion' written on it, you've found the alarm.
Central locking is a different system - the alarm merely connects in to it.
pkr, i find most of the control units are on the transmission tunnel behind stereo, just remove the cover panel on drivers or passenger side or both and its usually in a cradle on the trans tunnel, at least they are in my GTV's / Spiders. im open to being proven wrong though?
Google search a company called abacus alarms in london. Just sent them my meta box as had the same problem, all keys and no fobs. 24 hours later I have my box back, with 2 new fobs and the code card all done! £99.00 and done in no time! guy is called sam, really helpful