if(!isObject(rocketProjectile)){exec("./Weapon_Rocket Launcher.cs");}
if($AddOn__Weapon_Rocket_Launcher $= "-1"){schedule(1000,0,eval,"rocketlauncheritem.uiname = \"\";");}
Explanations:
if(NOT(One of the datablocks for Rocket Launcher exists)){Execute File to Create stuff}
if(Launcher Isn't Enabled){In one second: Make rockets item display name "" so it doesn't show up}