I don't believe that you are able to execute a remote file through CRON, PHP, or any other service on X10. You shouldn't do it anyways, because it's a huge risk to the security of your website and the server as a whole.
You can execute files on other servers using wget, assuming the other server is set up to execute the file AND the file is accessible via the web. What wget does is it requests the file, and requesting a php file usually causes the web server to run the file. (I.e. wget is like a browser except it doesn't render the file, but stores it instead.) Usually it is enough to run 'wget '.