<form name="Testform">
<input type="text" name="Eingabe" size="20" maxlength="6" value="" onKeyup="ist()"><br>
<input type="text" name="Datum" size="20" value="">
</form>
<SCRIPT LANGUAGE=JavaScript>
<!--
function ist() {
var str=document.Testform.Eingabe.value;
document.Testform.Datum.value= str.substring(0,2)+'.'+str.substring(2,4)+'.'+str.substring(4,6);
}
//-->
</SCRIPT>