<head>
<meta charset="utf-8" />
<title>test</title>
<style type="text/css">
div { position: absolute; width: 200px; height: 20px; border: 1px solid red; }
input { visibility: hidden; }
</style>
</head>
<body>
<div>
<input type="text" />
</div>
<script type="text/javascript">
document.getElementsByTagName("div")[0].onclick = function (){alert(1)};
if (this.dispatchEvent){
var evObj = document.createEvent('MouseEvents');
evObj.initEvent('click', true, true);
document.getElementsByTagName("div")[0].dispatchEvent(evObj);
}
</script>
</body>
Ну а для ИЕ fireEvent
http://help.dottoro.com/ljvtddtm.php