Redhat starts processes that it finds in /etc/rc[runlevel].d
For example if you are using run level 5 (graphical startup) you would use /etc/rc5.d
In this directory are a set of links to startup scripts in /etc/init.d. The name of the link is important. The first letter is K or S for Kill or Start. The next number is the order that the processes are started.
For example /etc/rc5.d/S99somecustomservice would be linked to /etc/init.d/somecustomservice
Hope this helps