Saumil, I started through the excellent instructions you provided, but I didn't have to go very far down the list. I unplugged the low-pressure switch and checked for continuity across the switch (rather than jump the wires). The switch showed perfect continuity. Figuring I needed to go on down the checklist, I removed my meter and reattached the wires to the switch. When I did that, the compressor clutch engaged and stayed that way. (The car was running at the time.) Apparently the problem was just a bad connection at the low-pressure switch.
Thanks for all the help.
-Brett