Mouse Orbit Improved (Rotating when Mouse Button is down)

Hello, I'm currently trying to make my camera only rotate when the middle mouse button is down and I'm finding it extremely hard to implement this within Mouse Orbit Improved. I know I have to use Input.GetMouseButton(2), however I'm not entirely sure what part of the code to split up in order to get the desired effect. Thanks if anyone can help! =)

 var target : Transform;
 var distance = 10.0;
  
 var xSpeed = 250.0;
 var ySpeed = 120.0;
  
 var yMinLimit = -20;
 var yMaxLimit = 80;
  
 var distanceMin = 1.5;
 var distanceMax = 15;
  
 private var x = 0.0;
 private var y = 0.0;
  
  
 @script AddComponentMenu("Camera-Control/Mouse Orbit")
  
 function Start () {
     var angles = transform.eulerAngles;
     x = angles.y;
     y = angles.x;
  
     // Make the rigid body not change rotation
        if (rigidbody)
         rigidbody.freezeRotation = true;
 }
  
 function LateUpdate () {
     if (target) {
         
         x += Input.GetAxis("Mouse X") * xSpeed * distance* 0.02;
         y -= Input.GetAxis("Mouse Y") * ySpeed * 0.02;
 
          y = ClampAngle(y, yMinLimit, yMaxLimit);
 
         
         var rotation = Quaternion.Euler(y, x, 0);
  
         distance = Mathf.Clamp(distance - Input.GetAxis("Mouse ScrollWheel")*5, distanceMin, distanceMax);
  
         var hit : RaycastHit;
         if (Physics.Linecast (target.position, transform.position, hit)) {
                 distance -=  hit.distance;
         }
  
         var position = rotation * Vector3(0.0, 0.0, -distance) + target.position;
  
         transform.rotation = rotation;
         
         transform.position = position;
 
     }
  
 }
  
  
 static function ClampAngle (angle : float, min : float, max : float) {
     if (angle < -360)
         angle += 360;
     if (angle > 360)
         angle -= 360;
     return Mathf.Clamp (angle, min, max);
 }