Question

I can’t disable the input, but I need to validate it no matter what the datepicker does.

$("#datepicker").datepicker({minDate: 0, maxDate: +7});

This produces the calendar I want, but won’t validate the input field.
I have the validator plugin already in use requiring fields so I’d like to stick to that.
This code will check if the field is required, but it won’t check the max date:

$(document).ready(function() {

  $("#form").validate({
   rules: {
    datepicker: {
      required: true,
      date: true,
       maxDate: 7
          }
         }
       });
    });

Answer 1

See my jsfiddle, your js code should work.
Enter 10/22/2011 into the input field and press submit. The max date will be checked.

You can remove the maxDate row in your rules, it will be ignored.