Sorry but no...
You need to modify the header response server side.
<?php
//Allows all AJAX requests from any domain
header('Access-Control-Allow-Origin: *');
?>
CAUTION!
If you add this it will allow all requests from any domain that this website is not hosted on. I would recommend you do more reading on this before using it. But if you don't have access to the server then its kinda moot any way.
Curious though your sending an Ajax request to a server you don't even have access to?