Issue with calling a function from another script on trigger. Using JavaScript.

So I'm making a simple weapon pickup at the start of a level, and I'm aiming to have the new weapon become the active weapon once it's been picked up. Removing it and giving it to my character were simple enough, however the switching automatically has become a bit of a problem.

 //M4A1Pickup.js
 function OnTriggerEnter (col : Collider)
 {
        print("Player picked up M4A1!");
        Destroy(gameObject);
        PlayerWeapons.hasPrimary = true;
        PlayerWeapons.SelectWeapon(0); //This here is the problem
 }

The function I'm trying to call is from the fps tutorial in the asset store and is as follows

 //PlayerWeapons.js
 function SelectWeapon (index : int)
 {
     for (var i=0;i<transform.childCount;i++)
     {
         // Activate the selected weapon
         if (i == index)
             transform.GetChild(i).gameObject.SetActiveRecursively(true);
         // Deactivate all other weapons
         else
             transform.GetChild(i).gameObject.SetActiveRecursively(false);
     }
 }

Obviously I get an error stating that an instance of type PlayerWeapons is required to access the non static variable SelectWeapon. Most of the previously answered questions I've found have said to use getComponent or make the variable/function static. When I try to make the function static I can no longer use transform and getComponent doesn't seem to work here either.

Some guidance would be much appreciated.