Event.observe(window, 'load', replaceLi);

function replaceLi(){
    var ol = $$('ol')[0];
    var i = 1;
    
    if(ol) {
        ol.descendants().each(function(element) {
            if(element.tagName == "LI") {
                element.style.listStyle = 'none';
                var nummer = '<div id="pfeil_'+i+'" class="special-ol">'+i+'.</div>';
                var alt = element.innerHTML;
                element.innerHTML = nummer+alt;
                i++;

            }
        });
    }
}