<script>
function SetEnd (TB) {
   if (TB.createTextRange){
     var FieldRange = TB.createTextRange();
     FieldRange.moveStart('character', TB.value.length);
     FieldRange.collapse();
     FieldRange.select();
   }
}
</script>

<form name="form1" action="somepage.asp" method="post">
<input type="text" name="city" value="lol" onfocus="SetEnd(this)">
<input type="submit" value="Submit">
</form>
<script language="JavaScript"> document.forms[0].city.focus(); </script>