Forcing "date" to use a locale other than the machine default
You can modify the environment date runs in. I don't know if this is the best way (the variables used in locale handling are numerous), but the following works:
$ LANG=de_DE dateMo 15 Okt 2012 09:34:12 EDT(January beat me to this answer by a minute or so, but I'll leave my answer up in the hopes that some will clarify which variable (LC_ALL, LANG, other) is most "appropriate".)