インストールしたら
;;
;; for mew
;;
;(autoload 'mew "mew" nil t)
;(autoload 'mew-send "mew" nil t)
;(setq mew-mail-domain-list '("kitakyu-techno-ctr.co.jp"))
;(setq mew-icon-directory "/usr/local/lib/mule/etc/mew")
;(setq exec-path (cons "/usr/local/bin/mh" exec-path))
;
(autoload 'mew "mew" nil t)
(autoload 'mew-send "mew" nil t)
(setq mew-mail-domain-list '("kitakyu-techno-ctr.co.jp"))
(setq mew-icon-directory "/usr/local/share/mule/etc/mew")
(autoload 'mew-user-agent-compose "mew" nil t)
(if (boundp 'mail-user-agent)
    (setq mail-user-agent 'mew-user-agent))
(if (fboundp 'define-mail-user-agent)
    (define-mail-user-agent
      'mew-user-agent
      'mew-user-agent-compose
      'mew-draft-send-letter
      'mew-draft-kill
      'mew-send-hook))

;(setq mew-demo nil)
;(setq mew-cc           "")

;(setq mew-fcc "fcc")
(setq mew-from "Takeshi FUJIKI <fujiki@kitakyu-techno-ctr.co.jp>")
;(setq mew-reply-to      "fujiki@kitakyu-techno-ctr.co.jp")
(setq menu-bar-tools-menu (make-sparse-keymap "Tools"))
(setq menu-bar-final-items (cons 'tools menu-bar-final-items))
(define-key global-map [menu-bar tools]
        (cons "Tools" menu-bar-tools-menu))
(define-key menu-bar-tools-menu [mew]
        '("Mew (Mail)" . mew))

;(setq mew-field-visible '("Subject:" "From:" "To:" "Date:"))
;(setq mew-field-other-visible nil)
;(setq mew-header-max-length 100)

を設定し、さらにコマンドラインでimsetupを実行して
~/.im/Configを作成し、設定する必要がある