[Moo] Help Moo111 - add/create a class in a sub tag

[ghazal]

Hi,
this is joomla related.
We need to create a class "toggler" and a class "element" in the
subsequent structure where they dont exist previously.

HTML :
***************************************************
<h3>Menu</h3>
                        <ul class="menuclassic">
                        <li class="parent">
                        <span class="toggler"><span>Separator 1</span></span>
                                <ul class="element">
                                        <li>
                                        <a href="#">
                                        <span>Article 1</span>
                                        </a></li><li><a href="#"><span>Article 
2</span></a>
                                        </li>
                                        <li><a href="#"><span>Article 
3</span></a></li>
                                        </ul></li>
                        <li class="parent">
                        <span class="toggler"><span>Separator 2</span></span>

                                <ul class="element">
                                <li><a href="#"><span>Article 4</span></a></li>
                              <li><a href="#"><span>Article 5</span></
a></li>


etc..
***************************************************

These 2 must be created:
<span class="toggler">
<ul class="element">

What we tried :
***************************************************
JS :
                window.addEvent('domready',function() {
var divparent = document.getElementById("leftcolumn");
var ulparent = divparent.getElementsByTagName("ul");


for(i = 0; i < divparent.getElementsByTagName("ul").length; i++) {
var classulparent = document.createAttribute("class");
classulparent.nodeValue = "menuclassic";
ulparent[i].setAttributeNode(classulparent);

}

for(i = 0; i < divparent.getElementsByTagName("ul").length; i++) {
for(j = 0; j < ulparent[i].getElementsByTagName("ul").length; j++) {
var ulenfant = ulparent[i].getElementsByTagName("ul");
var classulenfant = document.createAttribute("class");
classulenfant.nodeValue = "element";
ulenfant[j].setAttributeNode(classulenfant);
}
}

$$('span.separator').each(function(el) {
el.addEvent('mouseenter', function(){
                this.className+=" toggler";

                //alert(this.getProperty ( 'class' ));
        });
el.addEvent('mouseleave', function(){
                this.className=this.className.replace(new RegExp(" toggler\\b"),
"");
        });
});
});
***************************************************
This doesn't work.
We'd be very grateful for a hint in the right direction ...