<script type="text/javascript">
function bookmarksite(title,url){
if (window.sidebar) // firefox
    window.sidebar.addPanel(title, url, "");
else if(window.opera && window.print){ // opera
    var elem = document.createElement('a');
    elem.setAttribute('href',url);
    elem.setAttribute('title',title);
    elem.setAttribute('rel','sidebar');
    elem.click();
}
else if(document.all)// ie
    window.external.AddFavorite(url, title);
} </script>

<a href="java script:bookmarksite('Site Title', 'http://www.example.com')">Bookmark this site!</a>
Edit the body code by entering your site's title replacing Site Title, and then enter your site's homepage url to replace [url="http://www.example.com/"]http://www.example.com[/url]