Allright, we ended up fixing this ourselves.
For the record, in case anyone else runs into this problem, here's what we did:
We set up a function that uses a regex to search for any TABLE tag. We then strip out the attribute values for cellpadding and cellspacing (setting them to 0) and set the border to 1.
This allows the editors to now double-click the tables to edit them.
We then added a button that sets the border back to 0 after they're done editing.
Both these buttons are called outside of the editor and processed on the server-side. If I have the time, I may try and whip up a javascript version for client-side editing. I'm hoping this bug will be fixed in CuteEditor by then, though. ;o) ;o) ;o)