Inhibitor switch is Subaru's fancy-schmancey name for a range indicator sensor or, as in more colloquial (and partially correct) terms, a neutral start switch. With or without an alarm no manufacturer would want the liability of a car that would start in any gear. Can you say Mike Wallace or yellow journalism?
(for the record I still don't know why Audi doesn't own CBS)
The diagram I'm referencing is for a '93 SVX. They may have made changes to the alarm portion of the circuit but the minimal items included in the circuit will still be the ignition switch, the inhibitor switch (sounds like something most of my teenage girlfriends had) and the starter solenoid.
Beav