Go on http://savannah.nongnu.org to create an account and claim to be part of project as a Z-6PO for your language.
You can also read page [[Developer_FAQ#Get
.2Fupdate_the_development_CVS_version|Get/update the development CVS version]] to know how to use the GIT server to commit your changes on language files. But commits must be limited to changes for translations purposes.
This grade can be obtained quickly enough. Just ask it on mailing list.