Prova questa, io l'ho usata diverse volte:

<script language="JavaScript">
<!--
var i_scroll=0
var scrollSpeed=45 //Greater is, slower is the scroller
var step=2
var scrollheight=300 //It must have the same value of the height of the message
//If it is greater than this, determine a pause while cycling

function scrollwindow() {
window.scroll(0,i_scroll) //Scroll the page content
i_scroll+=step //Determine the speed of scrolling
if (i_scroll >= scrollheight) {i_scroll=0}
var timer= setTimeout("scrollwindow()",scrollSpeed)
}

function apri(pag,lingua){
location="ita/principaleazie.htm"

}

//-->
</script>
</HEAD>
<BODY ONLOAD=javascript:scrollwindow()>