Where=In /etc/init.d -or- /etc/rc.d there should be directories named rc[0-5].d place the startup script there.
How= Use sterm to copy the script there make sure you follow the naming convention in that directory S/K[00-100]nameofscript.
S starts the script.
K Kills the script.
Hope that helps.
PS it might be a good Idea to link your script into the rc[0-5].d directory that way you can move it to another runlevel without having alot of duplicate files.