Défilement iframe par boutton

<script language="javascript" type="text/javascript">
var Timer=null;
var Pas = 10;
function moveLayer(Sens) {
var Objet=document.getElementById("contenu");
if(parseInt(Objet.style.top) + (Pas*Sens)>0) {
clearTimeout(Timer);
}
else if(parseInt(Objet.style.top) + (Pas*Sens)<-(Objet.offsetHeight-document.getElementById("support").offsetHeight)) {
clearTimeout(Timer);
}
else {
Objet.style.top = (parseInt(Objet.style.top) + (Pas*Sens)) + "px";
}
Timer = setTimeout("moveLayer(" + Sens + ");", 30);
}
</script>

<div id="support" style="position:relative; width:1000px; height:900px; overflow:hidden; border:0px solid #000;">   
<div id="contenu" style="position:absolute; top:0;">
<iframe name scrolling="no" src="#"
style="width:800; height:9000;
frameborder:0;">

<div id="support" style="position:relative; width:1000px; height:900px; overflow:hidden; border:0px solid #000;">   
<div id="contenu" style="position:absolute; top:0;">
<iframe name scrolling="no" src="http://www.ebay.com"
style="width:800; height:9000;
frameborder:0;">
</iframe>
</div>
<div style="background-color:white; width:22px; height:50px; position:absolute; right:0; border-left:0px solid #000;">
<img onMouseOver="moveLayer(1);" onMouseOut="clearTimeout(Timer);" src="up_off.gif" style="cursor:pointer; position:absolute; right:0;">
<img onMouseOver="moveLayer(-1);" onMouseOut="clearTimeout(Timer);" src="down_off.gif" style="cursor:pointer; position:absolute; right:0; bottom:0;">   
</div>
</div>