From Stephan Huber,

"attached you'll find some modifications to Producer, osgGA and
osgProducer to enable Mac OS X support for

+ scrollwheels,
+ mightymouse-srollballs
+ new tracking-pads with scroll feature
+ tablet-support (pressure, proximity and pointertype) (Wacom only tested)

I think there was a bug in the windows-implementation of scroll-wheel
support (wrong order of ScrollingMotion-enum, casting problem) which is
fixed now.

The scrollwheel-code is a bit klunky across platforms, some devices on
OS X can report an absolute delta in pixel-coordinates not only the
direction, so for now there is scrollingMotion (which describes the
direction) and scrolldeltax and scrolldeltay. I decided to leave the
scrollingmotion-stuff to not break old code relying on this."

include/osgGA/EventQueue

@@ -56,6 +56,15 @@ class OSGGA_EXPORT EventQueue : public osg::Referenced
 
         /** method for adapting mouse scroll wheel events, placing this event on the back of the event queue. */
         void mouseScroll(GUIEventAdapter::ScrollingMotion sm);
+        
+        /** method for adapting mouse scroll wheel events, placing this event on the back of the event queue. */
+        void mouseScroll2D(float x, float y);
+        
+        /** method for adapting pen pressure events, placing this event on the back og the event queue.*/
+        void penPressure(float pressure);
+        
+         /** method for adapting pen proximity events, placing this event on the back og the event queue.*/
+        void penProximity(GUIEventAdapter::TabletPointerType pt, bool isEntering);
 
         /** method for updating in response to a mouse warp. Note, just moves the mouse position without creating a new event for it.*/
         void mouseWarp(float x, float y);