questo mi funziona su IE

codice:
<script type="text/javascript" language="JavaScript">
<!--
function getMousePosition(elm, e){
	if(!e) e=window.event;

	var vDoc=(document.documentElement && document.documentElement.scrollTop)?document.documentElement:document.body;

	var mouseX=(e.pageX)?e.pageX:e.clientX+vDoc.scrollLeft;
	var mouseY=(e.pageY)?e.pageY:e.clientY+vDoc.scrollTop;
    
   if (elm = 'miolink') {
     alert(mouseX+','+mouseY);
   }
}
if(document.layers) document.captureEvents(Event.CLICK);

</script>
?
per mozilla e FF sto ancora provando