We have a wiki server running Mac OSXS 10.6, and rather than have users type something like this:

http://bbox.beezwax.net/groups/bbox

which would be the standard URL, we instead wanted to use the much simpler:

http://bbox.beezwax.net/

First step was to create a virtual host. Then came some searching for what others had been using for redirects. I wasn't able to find an answer that was exact match (although others had asked the same question), and I was still having trouble getting the redirect right. Finally, I realized I had been over-engineering the the issue, and the Apache redirect was simply this:

RedirectMatch permanent /index.html /groups/bbox/