2002 AC Clutch needs R&R

2002 Mercury Mountaineer, 4.6 V8. The AC clutch is gone. I looked in my Chilton manual and it details how to R&R the AC compressor, but says nothing about the AC clutch. However, it does say that if you are putting in a new AC compressor, "the clutch may have to be transferred from the original to the new compressor," but doesn't say how one might do that. It would seem from that comment however, that the AC clutch should be able to be R&R'd separately. Has anyone done this? Can it be done with the compressor in place? (I hope so because I don't really want to discharge and recharge the system.) Is the AC clutch a common part available at Auto Zone and the like? Thanks in advance for your help.