datetime.phtml

<script src="<?php echo Mage::getBaseUrl('js')."calendar/calendar.js" ?>" type="text/javascript"></script>

<script src="<?php echo Mage::getBaseUrl('js')."calendar/calendar-setup.js" ?>" type="text/javascript"></script>

<link rel="stylesheet" type="text/css" href="<?php echo Mage::getBaseUrl('js') ?>calendar/calendar-win2k-1.css"  />

<?php echo $this->getLayout()->createBlock('core/html_calendar')->setTemplate('page/js/calendar.phtml')->toHtml();?>
<label for="date_picker_id"><?php echo $this->__('Your Date 1') ?> </label>

<input type="text" name="shipping_pickup_at_store_date" class="datetime" value=""/>

<label for="date_picker_id"><?php echo $this->__('Your Date 2') ?> </label>

<input type="text" name="shipping_pickup_at_store_date_2" class="datetime" value=""/>
<script type="text/javascript">
    // <![CDATA[

    jQuery(document).ready(

        function($)
        {
            $('input.datetime').each(function(){
                var randomNumber = Math.floor((Math.random() * 100) + 1);
                var element = $(this);
                $(this).before('<img style="" title="Select Date" id="date_select_trig_' + randomNumber+'" alt="" src="<?php echo $this->getSkinUrl("images/calendar.gif");?> "/>');
                Calendar.setup({
                    inputField: null,
                    daFormat: "%d/%m/%Y %H:%M:%S",
                    showsTime: true,
                    button: "date_select_trig_" + randomNumber,
                    align: "Bl",
                    singleClick : true,

                    onSelect: function(dateObj,selectedDate) {
                        $(element).val(selectedDate);
                        console.log(dateObj);
                    }
                });
            });
        }
    );
    // ]]>