ah, credo di aver capito... per caso così va?
codice:
<script type="text/javascript">
    Calendar.setup({
        dateStatusFunc :    function (date) { // disable weekend days (Saturdays == 6 and Subdays == 0)
                              return (date.getDay() == 0) ? true : false;
                            },
        inputField     :    "data_esame",     // id of the input field
        ifFormat       :    "%Y-%m-%d %H:%M:00",     // format of the input field (even if hidden, this format will be honored)
        displayArea    :    "vis_data_esame",       // ID of the span where the date is to be shown
        daFormat       :    "%A %d %B %Y ore %H:%M",// format of the displayed date
        align          :    "Bc",           // alignment (defaults to "Bl")
        weekNumbers    :    false,        // disabilito i numeri di settimana
        range          :    [2007,2008],
        showsTime      :    true,
        timeFormat     :    "24",
        step           :    "1",
        date           :    "08-16-2007"      
    });
</script>
ho invertito le due definizioni