First view a phpinfo page for the server and see if the entry for Server API says CGI. If it does then PHP may read configuration instructions from a php.ini file that it finds in the same location as the first PHP script processed on each request. To test this, create a file called php.ini in the same location as the phpinfo page and refresh the phpinfo(). If the file used as the configuration file is now listed as the file that you created, it is possible to use a custom php.ini file. You should then add a line to the php.ini file that says

zend_extension = /path/to/ioncube_loader_lin_5.2.so

Replace /path/to with the full path to where the Loader is located on the system, and if the server uses PHP 5.3, 5.4 etc., replace 5.2 with the correct number for the PHP version used. Lastly replicate the php.ini file in each location where scripts are located that are accessed directly by the browser.