Maemo Leste localization is inherited from the localization work by done Nokia. Many of our current translations therefore come from converting the existing packages from Maemo Fremantle into packages.
The source packages for our translations are located in our GitHub translation organizations: https://github.com/maemo-leste-translations
There is no documentation on how to contribute a new language yet, but we hope to write that soon. Also, some of the translations are not yet used, as our own software is not complete yet, so when contributed an initial new language it might make sense to focus on the strings that are actively in use.
We boost our localisation efforts with Weblate: https://hosted.weblate.org/projects/maemo-leste/
On Weblate people can contribute translation improvements, or even new languages, and pull requests should automatically be made against our repositories, so maintainers can simply merge it.