control.modal

Hi
  Hi is there anyone using control.modal
http://livepipe.net/projects/control_modal/
     I have the code like
<a
onclick="get_details(document.forms[0].sd_ticket_primary_assignee_group_id.value);"
href="#">select</a>

<script>

function get_details(group_id) {
alert('in function' +group_id);

  new Ajax.Request( '/popup/show_primary_assignee',{
      method: 'post',
        parameters: { group_id: group_id },
      onSuccess: function(request) {
         var response = request.responseText || "no response text";
         Control.Modal.open(response);
      }
    });
}
</script>

        Here my question is how can i specify width and height to the
modal window and also how can I close the window?

Sijo