Так проще
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="ru" lang="ru" dir="ltr">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=windows-1251" />
</head>
<body>
<div id="apslaed">Клик</div>
<script type="text/javascript">
function Onchange(Th){
alert('3434');
alert(Th.value)
}
document.getElementById("apslaed").attachEvent("onclick",function()
{
var newElem = document.createElement("div");
newElem.id = "sizeslide";
newElem.innerHTML = "<form id=\"fileload\" action=\"#\" method=\"post\" enctype=\"multipart/form-data\"><input type=\"file\" name=\"anyfile\" id=\"inpField\" onchange=\"Onchange(this)\"/></form>";
document.body.insertBefore(newElem, document.body.firstChild);
});
</script>
</body>
</html>