I have added an en_NZ translation which has a few of the spelling differences that we have down here.
Until a language interface is created add something like:
/* Set locale */
setlocale(LC_ALL, 'en_NZ');
bindtextdomain("laconica", './locale');
textdomain("laconica");
to index.php to allow you to test your new locale. I used http://www.poedit.net/ to edit the locale. Also see http://nz2.php.net/manual/en/function.setlocale.php#82288 is you're having issues getting you locale to work on linux.
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