you will need to edit the date picker javascript code.
the code may look like:
$(function(){
$('#datepicker_1').datepicker({
dateFormat: 'mm/dd/yy',
showAnim: 'show',
onClose: closeDatePicker_datepicker_1
});
});
you will need to add firstDay: 1,
$(function(){
$('#datepicker_1').datepicker({
firstDay: 1,
dateFormat: 'mm/dd/yy',
showAnim: 'show',
onClose: closeDatePicker_datepicker_1
});
});