You actually want to jump the harness. Unplug it from the sensor and put a piece of wire across the connector. Don't do it if it's an empty system, or you'll fry the compressor.
Guero, if your compressor won't engage for no apparent reason, check the WOT relay and its wiring socket. They are on the passenger fender kinda under the MAF. The wiring is very susceptible to getting baked and causing an open circuit or other issues. Sometimes just moving the relay around in your hand causes the AC to kick on.
Redoing the wiring or splicing in a new socket and relay are the common solutions if this is the issue.
An issue at this junction will cause jumping of the LPCS that Matt talked about to not work.
Get out your voltmeter and check for 12 volts at the low pressure cutout switch that you were told to jumper. No 12 volts, keep on looking...
Diagram courtesy of Tmoss & Stang&2birds
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.