Add quantity spinner

It would be very nice about usability if quantity field work only with two arrows (up/down).
So adding the arrows seems easy, just adding this code at the beginning of dc-ajax-shopping-cart.tpl.php

<script>
$(function() {
var spinner = $( "#block-dc-ajax-add-cart-ajax-shopping-cart table input[type=text]" ).spinner();
});
</script>

but the problem is how to implement the update automatically so to remove the button

can anyone help on this?