Как-то так:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link href="css/flexcrollstyles.css" rel="stylesheet" type="text/css" />
<script src="js/1.9.1_jquery.min.js"></script>
<script type="text/javascript" src="js/flexcroll.js"></script>
<script type="text/javascript" src="js/flexcroll-uncompressed.js"></script>
<script type="text/javascript">
function update(){
fleXenv.updateScrollBars();
}
</script>
</head>
<body>
<input type="button" onclick="update()" value="ok" />
<div style="width: 500px; height: 500px;" class="flexscroll">
</div>
</body>
</html>
И все равно при клике на кнопку fleXenv.updateScrollBars is not a function