aqui aqui !!! yo yo !!!
Código HTML:
<script language="javascript" type="text/javascript">
function fn_saltar(uno){
num = uno.value.length;
if (num==2)
document.getElementById("dos").focus();
}
</script>
<input type="text" id="uno" onkeyup="fn_saltar(this);" />
<input type="text" id="dos" /> !!!