function getSfEls(type, tag, parentId) {var sfEls =(parentId==null)?document.getElementsByTagName(tag):document.getElementById(parentId).getElementsByTagName(tag);type(sfEls);}

function suckerfish(type, tag, parentId) {
	if (document.all) { //MS IE
		if (window.attachEvent) {
			window.attachEvent("onload", function() { getSfEls(type, tag, parentId); });
		} else { //IE 5.2 Mac does not support attachEvent
	 		var save_window_onload_function = window.onload; 
			window.onload = function() { if (save_window_onload_function) save_window_onload_function(); getSfEls(type, tag, parentId)}
		}
	}
}

sfHover = function(sfEls) {
	for (var i=0; i<sfEls.length; i++) {
		sfEls[i].onmouseover= function() {this.className+=(this.className.length>0? " ": "") + "sfhover";}; 
		sfEls[i].onmouseout = function() {this.className=this.className.replace(new RegExp("( ?|^)sfhover\\b"), "");
		}
	}
}

suckerfish(sfHover, 'li', 'nav');