I know how but they are 2 ways and you have to be the host in private match u can call it a mod

first method is to get yourself weaponfiles and load them with a mod and lets say your secondary is a usp fmj just rename the usp_fmj weapon file to cheytac_mp now your usp is an intervention xd

2nd one is to create your own standard classes with the classTable.csv

example :
Code:
loadoutName,CLASS_CLASS1,CLASS_CLASS2,CLASS_CLASS3,CLASS_CLASS4,CLASS_CLASS5
loadoutPrimary,cheytac,cheytac,cheytac,cheytac,riotshield
loadoutPrimaryAttachment,fmj,acog,fmj,fmj,none
loadoutPrimaryAttachment2,none,none,none,none,none
loadoutPrimaryCamo,blue_tiger,red_tiger,red_tiger,red_tiger,none
loadoutSecondary,fal,barrett,barrett,m21,m21
loadoutSecondaryAttachment,shotgun,fmj,fmj,thermal,fmj
loadoutSecondaryAttachment2,none,none,none,none,none
loadoutSecondaryCamo,blue_tiger,red_tiger,red_tiger,orange_fall,red_tiger
loadoutEquipment,throwingknife_mp,throwingknife_mp,throwingknife_mp,throwingknife_mp,lightstick_mp
loadoutPerk1,specialty_fastreload,specialty_fastreload,specialty_fastreload,specialty_fastreload,specialty_fastreload
loadoutPerk2,specialty_bulletdamage,specialty_bulletdamage,specialty_bulletdamage,specialty_bulletdamage,specialty_bulletdamage
loadoutPerk3,specialty_extendedmelee,specialty_extendedmelee,specialty_extendedmelee,specialty_extendedmelee,specialty_extendedmelee
loadoutOffHand,concussion_grenade,concussion_grenade,concussion_grenade,concussion_grenade,concussion_grenade
loadoutDeathStreak,specialty_copycat,specialty_finalstand,specialty_finalstand,specialty_finalstand,specialty_finalstand,