code: function(control, callbacks, options) {
          OpenLayers.Handler.prototype.initialize.apply(this, arguments);
          this.wheelListener = OpenLayers.Function.bindAsEventListener(
              this.onWheelEvent, this
          );
      }
docs: Constructor: OpenLayers.Handler.MouseWheel
  
  Parameters:
  control - {<OpenLayers.Control>}
  callbacks - {Object} An object containing a single function to be
  called when the drag operation is finished.
  The callback should expect to recieve a single
  argument, the point geometry.
  options - {Object}