Don't allow to see date more than Past 4 week in AJax Calender Extender

Hello Friends

Actually what is my problem is i want to show only past 4 week date not more than past 4 week date using Ajax Calender Extender so how is it possible anyone suggest me to show only past 4 week calender where weekstart from Wednesday and weekend on Tuesday . Thanks in advance

<script type="text/javascript">
       function CheckWeekEndDay(sender, args) {
           var selecteddate = new Date(sender._selectedDate);
           if (selecteddate.getDay() != 2) {
               alert("Please Select a Valid Day");
               sender._textbox.set_Value('');
               return false;
           }
       }

       function onCalendarShown() {
           var cal = $find("calenddate");

           for (var i = 0; i < cal._daysBody.rows.length; i++) {
               var row = cal._daysBody.rows[i];

               for (var j = 0; j < row.cells.length; j++) {
                   if (j != 2) {
                       row.cells[j].setAttribute("class", "disablecal");
                   }
               }
           }
       }
   </script>

Tags: C++, Ajax, ASP.NET