iTween & gesture

Hello

I am using iTween's example pack

there is a slider that controls the movement of the Camera along a Path.

I want to replace the GUI slider(up) with a user drag up

I tried hacking the .js code but I'm not savvy enough

Here is the script on the Camera:

Thanks for looking

 public var movePath : Transform[];
 public var lookPath : Transform[];
 public var lookTarget : Transform;
 public var percentage : float;
 
 private var redPosition : float = .07;
 private var bluePosition : float = .13;
 private var greenPosition : float = .2;
 private var purplePosition : float = .0;
 
 //gui styling
 //public var font : Font;
 private var style : GUIStyle = new GUIStyle();
 
 
 function Start(){
 //    style.font=font;
 }
 
 
 function OnGUI(){
     percentage=GUI.VerticalSlider(new Rect(Screen.width-20,20,150,Screen.height-40),percentage,1,0);
     iTween.PutOnPath(gameObject,movePath,percentage);
     iTween.PutOnPath(lookTarget,lookPath,percentage);
     transform.LookAt(iTween.PointOnPath(lookPath,percentage));
     }
 //    if(GUI.Button(new Rect(5,Screen.height-25,50,20),"Red")){
 //        SlideTo(redPosition);
 //    }
 //    if(GUI.Button(new Rect(60,Screen.height-25,50,20),"Blue")){
 //        SlideTo(bluePosition);
 //    }
 //    if(GUI.Button(new Rect(115,Screen.height-25,50,20),"Green")){
 //        SlideTo(greenPosition);
 //    }
 //    if(GUI.Button(new Rect(115,Screen.height-25,50,20),"Purple")){
 //        SlideTo(purplePosition);
 //    }
 //}
 
 function OnDrawGizmos(){
     iTween.DrawPath(movePath,Color.magenta);
     iTween.DrawPath(lookPath,Color.cyan);
     Gizmos.color=Color.black;
     Gizmos.DrawLine(transform.position,lookTarget.position);
 }
 
 function SlideTo(position : float){
     iTween.Stop(gameObject);
     iTween.ValueTo(gameObject,iTween.Hash("from",percentage,"to",position,"time",2,"easetype",iTween.EaseType.easeInOutCubic,"onupdate","SlidePercentage"));    
 }
 
 function SlidePercentage(p : float){
     percentage=p;
 }
 

~be