Dit in de HEAD

<script type="text/javascript">
//<![CDATA[
function bookmark(anchor){
   if(window.external)
   {
       window.external.AddFavorite(anchor.getAttribute('href'), anchor.getAttribute('title'));
       return false;
   }
   return true;
}
//]]>
</script>

en dit in de body:

<a href="http://jeurl.com" rel="sidebar" title="Titelvanjesite" onclick="return bookmark(this)">Tekst</a>