I'm trying to predefine the var target : Transform; object within the script for use on a instantiated prefab.

var target : Transform;
var damping = 6.0;
var smooth = true;

@script AddComponentMenu("Camera-Control/Smooth Look At")

function LateUpdate () 
{
    if (target) 
    {

        if (smooth)
        {
            // Look at and dampen the rotation
            var rotation = Quaternion.LookRotation(target.position - transform.position);
            transform.rotation = Quaternion.Slerp(transform.rotation, rotation, Time.deltaTime * damping);
        }
        else
        {
            // Just lookat
            transform.LookAt(target);
        }
    }
}

function Start () {
    // Make the rigid body not change rotation
    if (rigidbody)
        rigidbody.freezeRotation = true;
}