Well, since I am in fact making a mod, and I finally got the code to work, I guess that I could do the proper coding if that ever comes into question... But, I never brought up this question becuse I really needed to know, but more becuase it was an interesting concept.
Anyway, it seems like it's in the part of code that give you the ammo in the gun, so for instance when you pick up the pistol there's an ammo clip in there. It appearantly checks if the map name is d3_c17_09, and the RPG's name is player_spawn_items. If both are true it will give the player 0 rockets, if they are false the player will be given 3 rockets (like normal).