<script>  
var selectedColor = '#CC3333';  
   
function addToSelectList( pList, pDisplay, pValue )  
{  
  var s = document.getElementById( pList );  
  s.length++;  
  s.options[s.length-1].text = pDisplay;  
  s.options[s.length-1].value = pValue;  
}  
   
function removeFromSelectList( pList, pValue )  
{  
  var s = document.getElementById( pList );  
  for ( i=0; i<s.length; i++ )  
  {  
    if ( s.options[i].value == pValue )  
    {  
      s.remove(i);  
      return;  
    }  
  }  
}  
  
function toggleEvent( pCell, pList, pDisplay, pValue )  
{  
  var cell = document.getElementById( pCell );  
  if ( cell.style.backgroundColor == "" )  
  {  
    addToSelectList( pList, pDisplay, pValue );  
    cell.style.backgroundColor = selectedColor;  
  }  
  else  
  {  
    removeFromSelectList( pList, pValue );  
    cell.style.backgroundColor = null;  
  }  
}  
</script>

javascript:toggleEvent( 'CELL#YYYY##MM##DD#', 
                        'P2_DATES', 
                        '#IDAY#, #IMONTH# #IDDTH# #YYYY#', 
                        '#DD#-#MON#-#YYYY#' )