Paste this code to the head of the form.html above the </head> tag. Adjust the #item1_date to the id of your datepicker element which also needs to be changed from the original id. Mine was originally item1_date_1

Add 0-6 to the daysToDisable = [6, 0]; array to disable specific days of the week.

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js" type="text/javascript"></script> <script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.6/jquery-ui.min.js" type="text/javascript"></script>
<script type="text/javascript">
$(function () {
// 0 = sunday, 1 = monday, 2 = tuesday, 3 = wednesday,
// 4=thursday, 5 = friday, 6=satday
var daysToDisable = [6, 0];
$('#item1_date').datepicker({
beforeShowDay: disableSpecificWeekDays,
minDate: 0
});
function disableSpecificWeekDays(date) {
var day = date.getDay();
for (i = 0; i < daysToDisable.length; i++) {
if ($.inArray(day, daysToDisable) != -1) {
return [false];
}
}
return [true];
}
});
</script>