[MM3-users] Mailman core: basic internationalization howto?

I would like to use Norwegian in the welcome/subscribe/unsubscribe/confirm etc messages from mailman3. For my current project I want all future mailing lists to have Norwegian as default. I find some sporadic info on the subject, but it's fair to say that I would like some simple instructions (e.g. what to copy from where to where, and which configs to change).