2003 Nissan Pathfinder help

I was asked to install a RS on a 2003 Nissan Pathfinder, but it has an extra factory installed security system which requires you to push a button on a keyfob and hold it while you turn the key to crank the engine. The owner claims that the dealer didn't give them any paperwork for this item so I have no way to find out exactly what it is or how it works. I assume that it is just a starter disable circuit that breaks the wire to the starter with a relay of some sort and the relay is switched only when you hold in the button on the keyfob. So not only do I have to bypass the immobilizer system I have to bypass this thing. It may be as simple as tapping into the starter wire on the other side of the relay but I don't know. Has anyone seen this and know exactly how it works? It also has the factory alarm installed and this thing appears to be seperate.