Ho trovato 10 minuti e ho fatto un esempio,spero che possa andarti bene.
Ecco il codice della pagina di prova.
codice:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 

"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>Documento senza titolo</title>
<style type="text/css">
/*<![CDATA[*/
ul.menu { list-style:none;}
ul.menu li{ display:inline;
			width:80px; /* Larghezza elemento del menu */
			float:left;}
ul.menu li div{ height:20px; /* Altezza riga menu */
				overflow:hidden;}
ul.menu a{ text-decoration:none;
			display:block;}
ul.menu a.bottom,ul.menu a.bottom:hover{color:#000000;}/* Colore principale */
ul.menu a.up,ul.menu a.up:hover{ color:#990000;} /* Colore superiore */
/*]]>*/
</style>
<script language="javascript" type="text/javascript">
/*<![CDATA[*/
var time=15;

function init_menu(id){
	var mn=document.getElementById(id);
	var dl=mn.getElementsByTagName('div');
	for (var i=0;i<dl.length;i++){  dl[i].scrollTop+=dl[i].offsetHeight;} 
}
function goUp(obj){
	obj=obj.getElementsByTagName('div')[0];
	for (var i=0;i<obj.offsetHeight;i++){ 

setTimeout('document.getElementById(\''+obj.id+'\').scrollTop-=1',i*time);}
					}
					
function goDown(obj){
	//clearTimer();
	obj=obj.getElementsByTagName('div')[0];
	for (var i=0;i<obj.offsetHeight;i++){ 

setTimeout('document.getElementById(\''+obj.id+'\').scrollTop+=1',i*time);}
					}
/*]]>*/
</script>
</head>

<body onload="init_menu('menu1')">
<ul class="menu" id="menu1">
	<li onmouseover="goUp(this)" onmouseout="goDown(this)"><div id="el1">Item 1Item 1</div>
	<li onmouseover="goUp(this)" onmouseout="goDown(this)"><div id="el2">Item 1Item 1</div>
	<li onmouseover="goUp(this)" onmouseout="goDown(this)"><div id="el3">Item 1Item 1</div>
	<li onmouseover="goUp(this)" onmouseout="goDown(this)"><div id="el4">Item 1Item 1</div>[/list]
</body>
</html>
e la sua versione online, per poterla vede in azione: demo

io l'ho provato su Firefox 2.0, IE 6 e Opera 9