How to use language pack?


I've installed the Directory plugin in an existing WordPress installation. This WP installation's already using a French language pack and I have this line in wp-config.php :
define('WPLANG', 'fr_FR');

I did a partial translation of directory.pot and I've named it, but all Directory's terms stay in English.

Are there translation instructions available?

Is there a complete French translaction available for this plugin?

Thank you.