How can i get this script to activate when my character touches it?

How can i get this script to activate when my character touches it, with out using a collision box?

#pragma strict

 var target : Transform;
 var smoothTime = 0.3;
 private var thisTransform : Transform;
 private var velocity : Vector3;
 var offsetAmountx : float = 10.00;
 var offsetAmounty : float = 10.00;

 function Start()
 {
     thisTransform = transform;
 }

 function Update()
 {
     thisTransform.position.x = Mathf.SmoothDamp( thisTransform.position.x, 
     target.position.x +offsetAmountx,velocity.x, smoothTime);
     thisTransform.position.y = Mathf.SmoothDamp( thisTransform.position.y, 
     target.position.y +offsetAmounty,velocity.y, smoothTime);
 }

Collision detection without colliders ? That’s a tricky one. You can check the distance every frames to simulate a sphere collider, but that’s more or less using a bazooka to shoot a duck don’t you think ?

You should create a script called Activator (eg), with a collider trigger that activates a gameObject when something collides with it, then destroy itself.