[Waqwaq root directory]/brain/_template_xlate.js and rename it to xlate-[***].js, where the asterisks stand for the ISO 639-3/B-alpha-3 language code.
[Waqwaq root directory]/brain/iso3166-1-a2-eng.js and rename it to iso3166-1-a2-[***].js, where the asterisks stand as above for the ISO 639-3/B-alpha-3 language code.
./brain/site.ini.js add the code and denomination of the new language to the language list in variable guiLanguageList. It should look like: var guiLanguageList = ["eng","English","ger","Deutsch","fra","Français","xxx","NewLanguage"];.
xlate-[***].js, iso3166-1-a2-[***].js and site.ini.js to the ./brain/ directory of the Waqwaq webservice hosted on your webserver.
xlate-[***].js fiels in other languages.
header.content section. See MapFileFormat > Metadata > header > content > contentLanguage and the sample georeferences file.