kodlar orada işte:

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.1/jquery.min.js"></script>
<script type="text/javascript" src="http://github.com/jonleighton/date_input/raw/master/jquery.date_input.js"></script>
<link rel="stylesheet" href="http://github.com/jonleighton/date_input/raw/master/date_input.css" type="text/css">
<script type="text/javascript">$($.date_input.initialize);</script>

bodynin içinde buda:
<input type="text" name="date" class="date_input">

kaynağa baksan görürdün, bunlarla yapılmış