IE에서만 지원하는 스크립트이고 다른 웹브라우저에서는 동작하는 스크립트가 없을 겁니다.

<script type="text/javascript">
var sidebarurl = "http://도메인"; // Change as required
var sidebartitle = "홈페이지제목"; // Change as required
var url = this.location;
var title = document.title;

function bookmarksite() {
if (window.sidebar && window.sidebar.addPanel){ // Firefox
window.sidebar.addPanel(sidebartitle, sidebarurl,"");
}
else if ( document.all ) { // IE Favorite
window.external.AddFavorite(url, title);
}
else if (window.opera && window.print) {
// do nothing
 }
else if (navigator.appName=="Netscape") {
alert("Please click OK, then press <Ctrl-D> to bookmark this page.");
}
 }

 if (window.sidebar && window.sidebar.addPanel) {
  document.write('<a href = "javascript:bookmarksite();" style="color:#A7A9AC;">즐겨찿기</a>');
  }
 else if (document.all) {
  document.write('<a href = "javascript:bookmarksite();" style="color:#A7A9AC;">즐겨찿기</a>');
 }
 else if (window.opera && window.print) {
document.write('<a href = "'+sidebarurl+'" title="'+sidebartitle+'" rel="sidebar" style="color:#A7A9AC;">즐겨찿기</a>');
 }
 else if (navigator.appName=="Netscape") {
  document.write('<a href = "javascript:bookmarksite();" style="color:#A7A9AC;">즐겨찿기</a>');
}
 </script>

감사합니다