the date picker is based pon jquery.
when you add a datepicker to the page, it will add a code block siomilar to this one:
$(function(){
$('#datepicker_1').datepicker({
dateFormat: 'mm/dd/yy',
showAnim: 'show',
onClose: closeDatePicker_datepicker_1
});
});
this code block allows you to specify date picker options.
you can add the max and minDate options, for example:
$(function(){
$('#datepicker_1').datepicker({
dateFormat: 'mm/dd/yy',
changeYear: true,
maxDate: 0,
minDate: new Date(1950, 1 - 1, 1),
showAnim: 'show',
onClose: closeDatePicker_datepicker_1
});
});
for a listing of other options that can be added see the jquery documentation:
datepicker/