ABS computer is under the passenger seat on the side closest to the passenger door. It's a chunky silver box, held with two screws (10mm hex head). Bolted to the bar running under the seat and the bump that holds the right rear seat bolt.
The security module (on my car, anyway) is a black box mounted under the rear deck, between the speakers. You have to remove the rear deck trim panel to access it.
Disclaimer: This is for a 1994 LSi - no guarantees that a '92 will have the same component locations
