в ~/.emacs
(XEmacs
  (set-language-environment "Cyrillic-KOI8")
  (select-input-method "cyrillic-jcuken")
)
(GNUEmacs
  (set-language-environment "Cyrillic-KOI8")
  (set-terminal-coding-system 'koi8-r)
  (set-keyboard-coding-system 'koi8-r)
)