I answered my own question, which I'll post here in case anyone else has the same question.
I'm using Windows 7. Go to this file location:
Users\[username]\AppData\Roaming\Adobe\InDesign\[Version]\[Language]\InDesign Shortcut Sets
Copy the keyboard shortcut file (*.indk) from the version 6.0 folder (which corresponds to CS4) to the version 7.0 folder (which corresponds to CS5).
Bad idea. Shorcut sets from CS4 don't translate well into CS5. You are much better off to make a new set from scratch.