You might want to check this thread out:
http://www.ozliberty.com/forums/showthread.php?t=5729

Anyways, what do you mean when you say "overrides the Subaru factory central locking"? Do you just mean the new alarm remote locks and arms the car rather than having to lock via the Subaru remote and then arm using the alarm remote?

If so, most alarm systems would do that.

I have a '98 Liberty and I recently purchased a Rhino RAv2 alarm and immobiliser (3-point) and the new remote they gave me controls the cars central locking and arms the alarm/immobiliser in one shot.

Heres some info on it if your interested:
http://www.rhinosecurity.com/content/pr … ochure.pdf

This is the company's best seller as its an adequate system for most peoples needs:
http://www.rhinosecurity.com/content/pr … ochure.pdf

I would definately recommend Rhino as I've been happy with the product thus far. They've got a good reputation in Australia. Steer clear from Brant - just ask some of the other members of this board...