Well, I re-downloaded over 5000 message headers going back to March 3,
and nowhere did I see you mention what car you're working on, so any help
more detailed than "it's right there" will have to wait for you to spill the beans.

Why should you? The few I've looked at closely all have the clutch internal
to the compressor and its drive belt pulley. The only wires are those in
the connector block(s) for the compressor itself.

It really helps to have a good shop manual for the car you're working on.
Do you have one?

As Tegger suggested, you will likely want to look at a shop manual or sorts
for any detailed kind of answers.  You may get lucky with:

http://www.autozone.com/shopping/repairGuide.htm

If I were to take my best guess though...  I would trace the piping from the
condenser (behind the rad) to the evaporator (should be an aluminum 'soup
can' looking thing (might be encased in plastic with a site glass).  Anyway,
there should be a valve on the low side of this evap with 2 wires on the
harness.  If you jump these two wires, you should effectively jump power to
the clutch.  As for the dash switch, yes, I meant the in-dash AC/FAN or
similar switch.  The relay that controls the compressor usually feeds both
from the low pressure switch and the dash switch.  More aften than not, your
problem will be found easily by checking both of these circuits.  As for
jumping the compressor clutch directly, I have never found any need as I
always use the low pressure switch harness first.  I would imagine it would
be easy enough to do though to test the harness that comes off the clutch
for +12V, GND and maybe a reference wire.  Again, Tegger's advice to consult
a schematic in a manual is very good advice indeed.  There's no substitute
for looking at the proper schematics.
Good luck,
Andrew.