Black Ops ps3. How to create a custom match with custom classes?

I'm trying to creat a custom match in Black Ops on ps3. I am able to modify the value of everything in the custom classes execpt the primary and secondary weapons. I go to Private Match -Edit Game Options- class editor. i switch to "costum classes". from here i go to edit class loadout. there are some games that people have created without primary weapons, limited ammo, more ammo or with multiple lethal grenades. Some even have unlimeted RPG ammo.How do I ajust the value of those items? I know how to change the perks and killstreaks.