Please help in changing a script! Need to add a trigger enter function!

I have a Collect Papers script from alucarj, but I need it changed. Here it is...

 #pragma strict
 @script RequireComponent( AudioSource )
 
 var papers : int = 0; // counter of how many papers collected
 var papersToWin : int = 8; // total number of papers in the scene
 
 var distanceToPaper : float = 5.5; // maximum distance that the raycast will detect
 var sphereRadius : float = 1.0; // the width of the sphere that is being SphereCast
 
 public var scaleTimerMax : float = 1.5; // how fast the paper disappears
 
 var paperSound : AudioClip;
 
 var enemyScript : NPCMovement;
 
 var musicManagerScript : MusicManager;
 
 
 private var currentPaperMaterial : Material;
 
 public var paperDisplayObject : Transform;
 public var paperDisplayLight : Light;
 public var paperDisplayParticles : ParticleEmitter;
 
 private var startPos : Vector3;
 private var startScale : Vector3;
 
 private var particleStartPos : Vector3;
 
 
 function Start() 
 {
     if ( !enemyScript )
     {
         Debug.LogWarning( "No Enemy Script in the Inspector" );
         var nme : GameObject = GameObject.Find( "Enemy" );
         enemyScript = nme.GetComponent( NPCMovement );
     }
     
     if ( !musicManagerScript )
     {
         Debug.LogWarning( "No Music Manager Script in the Inspector" );
         var mmngr : GameObject = GameObject.Find( "MusicManager" );
         musicManagerScript = mmngr.GetComponent( MusicManager );
     }
     
     if ( !paperDisplayObject )
     {
         Debug.LogWarning( "No paper Display Object in the Inspector" );
         paperDisplayObject = GameObject.Find( "PaperDisplayObject" ).transform;
     }
     
     if ( !paperDisplayLight )
     {
         Debug.LogWarning( "No paper Display Light in the Inspector" );
         paperDisplayLight = GameObject.Find( "PaperViewSpotlight" ).light;
     }
     
     if ( !paperDisplayParticles )
     {
         Debug.LogWarning( "No paper Display Particles in the Inspector" );
         paperDisplayParticles = GameObject.Find( "DustParticleEffect" ).particleEmitter;
     }
     
     paperDisplayObject.renderer.enabled = false;
     paperDisplayLight.enabled = false;
     paperDisplayParticles.emit = false;
     
     particleStartPos = paperDisplayParticles.transform.localPosition;
     
     startPos = paperDisplayObject.localPosition;
     startScale = paperDisplayObject.localScale;
 }
 
 
 function Update() 
 {
     if ( Input.GetMouseButtonDown(0) || Input.GetKeyDown( KeyCode.E ) )
     {
         var hit : RaycastHit;
         
         var rayOrigin : Ray = Camera.main.ScreenPointToRay( Vector3( Screen.width * 0.5, Screen.height * 0.5, 0 ) );
         
         if ( Physics.SphereCast( rayOrigin, sphereRadius, hit, distanceToPaper ) )
         {
             //Debug.Log( "SphereCast Hit : " + hit.collider.gameObject.name );
             //Debug.DrawLine( Camera.main.transform.position, hit.point, Color.red, 1.5 );
             
             if ( hit.collider.gameObject.name == "Paper" )
             {
                 //Debug.Log( "SPHERE hit Paper for sure" );
                 
                 papers += 1;
                 
                 // play paper has been picked up sound
                 audio.PlayClipAtPoint( paperSound, hit.point );
                 
                 // destroy the paper
                 Destroy( hit.collider.gameObject );
                 
                 // tell enemy to follow closer
                 enemyScript.ReduceDistance();
                 
                 // tell enemy to teleport now (if you want)
                 enemyScript.TeleportEnemy();
                 
                 // tell the player they go mad quicker
                 gameObject.SendMessage( "DecreaseHealthDecayRate", SendMessageOptions.RequireReceiver );
                 
                 // change the music based on the number of papers collected
                 if ( papers == 2 )
                 {
                     musicManagerScript.PlayMusicTrack( 1 );
                 }
                 else if ( papers == 4 )
                 {
                     musicManagerScript.PlayMusicTrack( 2 );
                 }
                 else if ( papers == 6 )
                 {
                     musicManagerScript.PlayMusicTrack( 3 );
                 }
                 else if ( papers == papersToWin )
                 {
                     Debug.Log( "You have collected All Papers !" );
                     
                     // load Win Scene here !!!!
                     Application.LoadLevel( "SceneWin" );
                 }
                 else if ( papers == 0 )
                 {
                     musicManagerScript.PlayMusicTrack( 0 );
                 }
                 
                 // set current paper material
                 currentPaperMaterial = hit.collider.gameObject.renderer.material;
                 
                 DisplayPaper();
             }
             
         }
     }
 }
 
 
 function DisplayPaper() 
 {
     // reset the size
     paperDisplayObject.localPosition = startPos;
     paperDisplayObject.localScale = startScale;
     
     paperDisplayParticles.transform.localPosition = particleStartPos;
     
     // --
     
     paperDisplayObject.renderer.material = currentPaperMaterial;
     
     paperDisplayObject.renderer.enabled = true;
     paperDisplayLight.enabled = true;
     paperDisplayParticles.emit = true;
     
     // --
     
     var scaleTimer : float = 0.0;
     //var scaleTimerMax : float = 2.5;
     
     var isScaling : boolean = true;
     
     while ( isScaling )
     {
         scaleTimer += Time.deltaTime;
         
         if ( scaleTimer > scaleTimerMax )
         {
             isScaling = false;
         }
         
         var scaleFactor : float = ( scaleTimerMax - scaleTimer ) / scaleTimerMax;
         
         paperDisplayObject.localScale.y = startScale.y * scaleFactor;
         
         // setting the scale
         var newPosY : float = startPos.y + ( ( startScale.y * 0.5 ) - ( paperDisplayObject.localScale.y * 0.5 ) );
         
         // adjusting the position
         paperDisplayObject.localPosition.y = newPosY;
         
         paperDisplayParticles.transform.localPosition.y = particleStartPos.y + ( startScale.y - paperDisplayObject.localScale.y );
         
         // retile the texture
         currentPaperMaterial.mainTextureScale = Vector2( 1.0, scaleFactor ); // change the scaling of the texture
         currentPaperMaterial.SetTextureOffset( "_MainTex", Vector2( 0.0, 1.0 - scaleFactor ) ); // change the UV positions of the texture
         
         // next frame
         yield;
     }
     
     // --
     
     // effect is over, 
     // reset the light and renderer
     paperDisplayObject.renderer.enabled = false;
     paperDisplayLight.enabled = false;
     paperDisplayParticles.emit = false;
     
     currentPaperMaterial.mainTextureScale = Vector2.one;
     currentPaperMaterial.SetTextureOffset( "_MainTex", Vector2.zero );

In the function Update the third line is an if statement, but I don't want it to work after a mouse click. I need it to get enabled after colliding a trigger collider on a paper. But I'm quite new to scripting, trying to do it myself just won't work. Help please!