First go in to your root\usermaps\mapname then create a new folder called gamedata and inside of that folder create a folder of weapons inside of that folder create a folder called zm.
Next locate your zm_levelcommon_weapons.csv file in root\share\raw\gamedata\weapons\zm and copy that file.
Then paste that file into root\mapname\gamedata\weapons\zm.
Then i recommend downloading a program called Apache OpenOffice and when running the installation you will have options on what to download, do ONLY Calc and nothing else only check calc.
Then edit the zm_levelcommon_weapons.csv with openoffice and under column "J" is determining whether it is in the box or not, just put false for not in the box or true for in the box.
Hope this helped out!