If you want to allow multiple weapon choices in Nitmod it can be as simple as changing the cvar in your server configuration.
Set g_dualSMG 2
g_dualSMG
(Bitflag) Allow players to carry a 2nd SMG (MP40 or Thompson). This option does NOT work for CovertOps AND Soldiers.
0 : Disable
1 : Enable
2 : Drop both primary weapons when players go into limbo mode (flag 1 must be enabled) This will allow you to use the grenade launcher and the mp40/thompson