var pos=0;
var speed=40; 

scrollIt = function() {

document.getElementById('scroll_thumbs').style.backgroundPosition=pos+'px 13px';
pos--;  // specifies left / right or top / bottom.
setTimeout('scrollIt()',speed);
 }

if(window.attachEvent) { // IE
window.attachEvent("onload",
scrollIt);
} else { // DOM Level 2 -- everything but IE
window.addEventListener("load",
scrollIt, false);
}