As root run:
/sbin/chkconfig --add mysqld
/sbin/chkconfig --level 2345 mysqld on
then run
/sbin/chkconfig --list
to check everything was set correctly.
Sources:
http://spicysquid.blogspot.com/2007/01/adding-unix-services-on-startup.html
http://fedorasolved.org/Members/opsec/installing-configuring-mysql-server
