MY TA (MARK FUGE) FOUND THIS MOUSE WHEEL CODE ON THE WEB SEVERAL YEARS AGO.  I JUST RAN IT ON MY IMAC AND IT WORKS.  THE CITATION FOR THE WHEEL CODE IS IN THE COMMENT.  I HOPE THIS HELPS.  JIM

int wheelRotationCounter; 

void setup( )
{
  size(100, 100);
  fill( 0 );
  textAlign(CENTER);
  textSize( 24 );

  wheelRotationCounter = 0;

  mouseWheelSetup();  // Responsible for Wheel Listener
}

void draw()
{
   background( 255 );
   text( wheelRotationCounter, width/2, height/2 );
}

// Uses an inner class to initialize and add the listener.
// Modified from code found on:
// http://processing.org/discourse/yabb/YaBB.cgi?board=Syntax;action=display;num=1110627607
void mouseWheelSetup()
{
    addMouseWheelListener( // the rest of of this is acutally the argument list for the function call
            new java.awt.event.MouseWheelListener()
            {
                 public void mouseWheelMoved(java.awt.event.MouseWheelEvent evt)
                 {
                   wheelRotationCounter += evt.getWheelRotation();
                 }
            }
   ) // this is the end of the argument list
   ;    // this single semicolon is the entire, complete function body
}

Thanks a lot man, this looks great.

TA is a teaching assistant -- basically a student who know more than me -- the prof...

Best
Jim