così funziona su FF2.0 e IE6.0 
codice:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>...</title>
<script type="text/javascript">
function inizia()
{
var paperino = document.getElementById( "paperino" );
var pluto = document.getElementById("pluto");
var form = document.createElement( "form" );
form.name = "modulo";
form.action = "";
var input = document.createElement("input");
input.type = "text";
input.name = "campo";
input.id = "pippo";
input.value = "";
if (window.XMLHttpRequest) {
input.setAttribute( "onblur", "test_alert()" );
} else {
input.setAttribute( "onblur", function(){test_alert()}, true );
}
form.appendChild(input);
paperino.appendChild(form);
document.getElementById("pippo").focus();
}
function test_alert(){ alert('pippo'); }
</script>
</head>
<body onload="inizia()">
<div id="paperino"></div>
</body>
</html>