Attached Link: CagePage via Archive.org

One way is to lock everything that you don't want to move, then unlock again. [Ockham](http://ockhamsbungalow.com/Python/) has a script that will help with that, to save you going to every body part in turn.

(I'm sure there was a script that would apply a pose selectively, but I can't recall it now and would quite like to know where it is myself. ;)

Edit: found it! Cage's Partial Pose Application should do it. His download page is offline at the moment, but you can get it from the Wayback Machine.