If your language is not configured into Aegir, it needs to be added to snippet /NemeinLocalization/init array $nemeinlocalization_languages. The format is the following:

"Polish" => Array ("library" => "pl", "locale" => "pl_PL", "localname" => "Polski", "encoding" => "ISO-8859-2"),

Please send this line to us so we can include it to the NemeinLocalization distribution!
Once language is configured in, just log in as admin and go to Front page -> configuration -> translation tool and select your language
You will be presented with the localization editor. Translate all strings and commit the changes
Once the translation is complete you need to enable it as selection in Aegir. For this, again edit snippet /AegirCore/lib/localization array $nemeinlocalization_available The format is the following:

"English","Finnish","Polish","My Language"

We will make the same addition in Aegir once your complete language library is added into the Aegir distribution
Choose the language from Front page -> configuration -> language, and test the translation thoroughly.
Once the translation is complete send it to us in repligard package for inclusion into the main distribution:
- Check the database ID for snippetdir /AegirCore/Localization/AegirCore/mylang
- Export that language with repligard
- Send the exported package to us or nadmin-dev
Aegir CMS is available in your local language!

After this the language library needs to be kept updated with new Aegir releases. We will start making prereleases of Aegir available for all translators so that they have time to translate all new strings before actual release.