In the interest of expediency I have accepted a partial victory. I performed a fresh installation of Zimbra and created the user accounts (as previously mentioned there are less than a dozen accounts). I snooped into messages in each of the message store directories to identify which branches were associated with which users. I then injected the messages into a Recovery folder in the new accounts according to "Method 1" in
this post. The users will have to reconfigure their settings and address books cannot be recovered, but their email history is intact.
On a related note, my personal account on this server was not lost because I was using Zimbra Desktop 2.0. I made sure NOT to create an account on the new server with the same username/password as I previously had (or the sync would wipe out the local offline cache) but rather created a temporary account. From there I could copy folders, contacts, etc. all without losing the metadata like tags to the temporary account. The process is tedious but worthwhile to me.
Thanks to everyone for their assistance.