The best solution here is to reduce your ePO DB size. See KB51873 for instructions shrinking the ePO DB. The instructions are written for ePO 4.0 but they are essentially the same for ePO 4.5. None of these steps require access to the ePO console.
You can certainly migrate the ePO DB. Once you detach the DB from the current SQL server and restart the ePO services ePO will no longer be able to connect to the DB and should allow you to access the core/config page without prompting for a password.
Thanks Jeremey, that worked great. I detached the database and then was able to access the core config page. From there it was a simple case of restoring the database in SQL 2005 and repointing EPO. Thanks again.