javascript finger slide detection

I'm trying to create a sliding checkbox like the one on the iphone.

I started with this script:

$('input[type=checkbox]').live('touchstart', function (e) {
            down_x = e.originalEvent.touches[0].pageX;
            $('input[type=checkbox]').live('touchmove', function (e) {up_x = e.originalEvent.touches[0].pageX;
            if ((down_x - up_x) > 1)  {$(this).change()}});
            });

But it does not seem to work. Any idea on how to implement this?