How to downgrade to MySQL 4.0 from 4.1 (Linux/rpms)
If you need mysql 4.0 installed instead of 4.1, you can remove 4.1 and install 4.0 by following this guide. This guide will wipe out any databases, so you'll need to make backups if you've already setup your databases
rm -f MySQL*
./mysql.sh rootpass da_admin daadmnpass
can be anything you want. This is where they are set, so you can use any passwords you want for them. The installer will ask you to delete the data. You need to select 'y' (yes) to delete the data. If you've done this before you may need to manually delete /var/lib/mysql first.