Good question... I'm not aware of any such script, but it should be relatively easy to derive one from an existing script, assuming you avoid al lthe traps and realyl do not nest your comps in more than one otehr comp. Perhaps simply ask at AENhancers.com or contact one of the guys on AEScripts.com directly....
I'm having a severe case of deja vu. I think I might have posted this question twice.
At any rate, I found a two-step solution to this:
Apply Un-Precompose plug-in to bring my pre-comp layer back into the comp. (This plug-ins is awesome and should be built into AE!)
http://www.videocopilot.net/tutorials/t ... se_script/