Jeff,
When I first installed DA, I had a problem with mysql so I asked DA Support how to reinstall it. They sent me instructions to run the mysql.sh script in ..../directadmin/scripts and that installed MySQL 5 for me.
PS. I've had no problems with MySQL 5 (except the join issue with osCommerce and dotProject) I expect more projects to include mysql5 compatible code over time so this will be less and less of an issue. I think fixing the scripts is less hassle than installing an old version of MySql.
When I first installed DA, I had a problem with mysql so I asked DA Support how to reinstall it. They sent me instructions to run the mysql.sh script in ..../directadmin/scripts and that installed MySQL 5 for me.
PS. I've had no problems with MySQL 5 (except the join issue with osCommerce and dotProject) I expect more projects to include mysql5 compatible code over time so this will be less and less of an issue. I think fixing the scripts is less hassle than installing an old version of MySql.