If you don't have shell access to your server and can't modify or create .htaccess files that you can always use the set_include_pathfunction. Note that you may already have some value set for your include_path so it may be a good idea to follow the model below to append the new values, instead of overwriting the entire path:

$clientLibraryPath = '/path/to/ZendGdata/library';
$oldPath = set_include_path(get_include_path() . PATH_SEPARATOR . $clientLibraryPath);

Note: Please refer to the PHP manual pages for more details on the set_include_path function.

require_once 'Zend/Loader.php';
Zend_Loader::loadClass('Zend_Gdata');
Zend_Loader::loadClass('Zend_Gdata_ClientLogin');
Zend_Loader::loadClass('Zend_Gdata_Photos');
Zend_Loader::loadClass('Zend_Http_Client');