Thread:Project:Support desk/Adding support for an "unrecognised" language

I'm working on a wiki-dictionary for the Balinese language which is listed here as an unrecognised language. Can someone point me to some resources on how I can go about adding support for this language? I understand that I can add it to $wgExtraLanguageNames, but what is the proper procedure for adding a new message file? I think this should be sufficient to get it to play nice with Universal Language Selector, but if anyone has any experience here I'd appreciate the advice. Thanks