Sorry, forget my previous post. We do have a partial Latin language pack since over a year now, contributed by Nick, a Google Highly Open Participation Project stutent.
It should be there on the language page in the administration block, ready for installation on your site. Are the other available language packs visible?
You can download it manually from http://download.moodle.org/lang16/ , unzip it and add it to your moodledata/lang folder if you have problems installing it from the administration block.