init of player:
this addeventhandler ["Fired",{if {_this select 1 in ["weapon"]) then {do something}}]
where weapon is the classname of players primary weapon. You could also put ["weapon1","weapon2","weapon3"] and so on for different types of primary weapons, and _this select 2,3,4, or 5. 2 is secondary (AT Weapon), 3 I think is riffle grenade, 4 is handgrenade, smokeshell, and i think "put", and i dunno what 5 is. "do something" is whatever you want to do, kinda like activation feilds, and you could also execute a script.
In trucks init:
this addaction ["Take Clothes","script.sqs"]
where script.sqs is the script activated by the action. It must be a script tho but anything you can do in an activation feild you can do in a script (except setidentity, but thats irrelevent)