"To record audio from the selected camera to the audio track, select Audio Follows Video in the Multi-Camera Monitor panel menu. Deselect this option to record audio from the audio track selected in the source sequence."
A quote from the Pr CS5.5 help page "Editing multi-camera sequences"
Wow, thanks. That was so simple and I had just skimmed right by it!
Good Grief! Now that I know the answer, I can find it all over the place. But before, I got so many google references that just told me it couldn't be done! That made me think the answer must be obscure -- when it was really simple, and should have been obvious to me.
The lesson seems to be: do more work looking around the panels and menus of the program itself before trying to look in "help" or "google".
Thanks, again, Jerry, for your consideration.