Mouse Orbit Script with mecanim & turning character

Hello! At start: sorry for my english but I'm a random noob from Poland :P I need help with enchanting Mouse Orbit Script. My game character should rotate with camera only when he walking/jogging. I want make effect like in Devil May Cry or Assassin's Creed. When I move camera to left and push "W" button my characters should be back to me. This is FRAGMENT of my code (it works but have a mistakes):

      var rot : Quaternion = cam.rotation;
      var cam : Transform;
         
         function Update ()
     {
         if(walk > 0)
         {
         transform.rotation.y = rot.y;
         }
     }