Pointers in function parameters

How to pass a pointer to structure to a function? For example in this function I need to change Vector3 value:

function ChangeVector( vec : Vector3 ) { vec.x = 0; }

function Main( ) { var vec = Vector3( 1, 1, 1 ); ChangeVector( vec );

... vec.x should be 0.

As far as I look at Collider.Raycast which is:

function Raycast (ray : Ray, out hitInfo : RaycastHit, distance : float) : bool;

and where RaycastHit is structure it is possible to do it.

PS: Is it possible to do this for simple variables like "int"?