This just feels dirty :)

jQuery date picker multiple dateFormats.js

// Add support for an alternative (second) dateFormat to the jQuery datepicker
(function () {
	var oldMethod = $.datepicker.parseDate;
	$.datepicker.parseDate = function () {
		var dateValue = Date.parseExact(arguments[1], 'ddMMyyyy');
		if (dateValue) {
			return dateValue;
		}
		return oldMethod.apply(this, arguments);
	};
})();