I'm not to familiar with SysV scripts included with RedHat, but you could modify /etc/rc.d/rc.S (or whatever the runlevel startup script is )
add in something like:
( If you aren't familiar with coding that's the bash script equivelant of saying 'if specified file exists, execute it' )
if [ -x /etc/rc.d/rc.modules ]; then
Then you can make a file in /etc/rc.d called rc.modules that contains the module installation commands.
You don't of course have to name the file rc.modules, but that's what it is in Slackware, so it can't be bad! ;D