93 yj
if it's a YJ you'd need to cut the +12v power side going to the coil of the ASD relay and connect you alarm/immobilizer cutoff relay in there. What that would do is similar to taking out the power going to the ignition coil, the fuel pump relay and the positive side of the fuel injectors (which are controlled by the PCM by providing ground individually to each of them). The other side of the coil for the ASD relay is connected to the PCM and gets ground when the motor is running or it rotates (when you crank it for example), if the ASD relay has no power then there's no fuel or spark. You can do this at the ignition key but in that case it does not account for being "jumped" by a thief
EDIT: like he ^ said
the ASD relay is in the PDC by the battery, you have 12v in the run and crank position to it and ground given by the PCM on the coil side. fairly simple to do, on a '95YJ the +12v keyed is white with yellow stripe (EDIT: actually it's dark blue color for the +12v ASD coil side according to the '95 FSM), not sure if that's the same on a 93 or not.