how to apply checkbox in multiselect dropdown

I am new php guy. i need to apply checkbox in multiselect dropdown but not success. I am create mutiselect dropdown using zend form. but not apply checkbox in this multiselect dropdown. so please help

 <?php echo $this->formSelect('ctr_partnerId', $expPartId, array('class' => 'select_input', 'multiple' => true, 'size' => 10), $this->usrName); ?>

I am using jquery

                   <script type="text/javascript" src="http://ift.tt/1fEahZI"></script>
<script type="text/javascript" src="http://ift.tt/1L4Jne4"></script>
<script src="http://ift.tt/1EzpXJJ"
    type="text/javascript"></script>




<script>
                $('select[multiple]').multiselect({
                includeSelectAllOption: true,
            });
</script>