<SCRIPT language=javascript>
var currentpos,timer;

function initialize()
{
timer=setInterval("scrollwindow()",10);
}
function sc(){
clearInterval(timer);
}
function scrollwindow()
{
currentpos=document.body.scrollTop;
window.scroll(0,++currentpos);
if (currentpos != document.body.scrollTop)
sc();
}
document.onmousedown=sc
document.ondblclick=initialize
</script>

说明：加在网页代码的<body></body>里面即可实现．效果是双击自动滚屏，单击停止.