OK, I found that in order to switch to a different database, I need to uninstall and reinstall MediaBin Server, and then choose that database.
That is not true AT ALL. I would strongly recommend that you hire a consultant or contact Interwoven CSO or at least Interwoven Support to get this accomplished. I am not sure how familiar you are with administering MediaBin but from your posts it seems very less. This is something CSO/Support does very often for customers.
I am not the one that wrote the documentation but I have first hand experience of not being successful at uninstalling and reinstalling it. The better approach is using the administrative applet. You will have to create an ODBC connection before doing that and make the new DB as the default in that ODBC configuration.