SKK で旧字旧かなと新字新かなを切り換へられる設定を書いた．

以下を home directory に置く：

ldic_kyuji.dic --- 北極三号改の辞書 npiiii.l.euc をこの名にしておく．
udic_kyuji.dic --- 旧字旧かなの user 辞書．
udic_kyuji.dic.BAK --- 旧字旧かなの user 辞書の backup.

ldic_shinji.dic --- SKK-JISYO.L をこの名にしておく．
udic_shinji.dic --- 新字新かなの user 辞書．
udic_shinji.dic.BAK --- 新字新かなの user 辞書の backup.

以下を init.el に記述する：

init.el

(setq skk-large-jisyo "~/ldic_kyuji.dic")
(setq skk-jisyo "~/udic_kyuji.dic")
(setq skk-backup-jisyo "~/udic_kyuji.dic.BAK")

(defun kyu-shin (x) (replace-regexp-in-string "kyu" "shin" x))
(defun shin-kyu (x) (replace-regexp-in-string "shin" "kyu" x))

(defun shinji-to-kyuji nil
  (interactive)
  (progn 
    (skk-mode -1)
    (skk-save-jisyo)
    (setq lub (list skk-large-jisyo skk-jisyo skk-backup-jisyo))
    (setq newlub (mapcar (function shin-kyu) lub))
    (setq skk-large-jisyo (nth 0 newlub))
    (setq skk-jisyo (nth 1 newlub))
    (setq skk-backup-jisyo (nth 2 newlub))
    (skk-mode 1)))

(defun kyuji-to-shinji nil
  (interactive)
  (progn 
    (skk-mode -1)
    (skk-save-jisyo)
    (setq lub (list skk-large-jisyo skk-jisyo skk-backup-jisyo))
    (setq newlub (mapcar (function kyu-shin) lub))
    (setq skk-large-jisyo (nth 0 newlub))
    (setq skk-jisyo (nth 1 newlub))
    (setq skk-backup-jisyo (nth 2 newlub))
    (skk-mode 1)))

(defun toggle-jitai nil
  (interactive)
  (cond 
   ((and 
    (equal skk-large-jisyo "~/ldic_shinji.dic")
    (equal skk-jisyo "~/udic_shinji.dic")
    (equal skk-backup-jisyo "~/udic_shinji.dic.BAK"))
   (shinji-to-kyuji))

   ((and 
    (equal skk-large-jisyo "~/ldic_kyuji.dic")
    (equal skk-jisyo "~/udic_kyuji.dic")
    (equal skk-backup-jisyo "~/udic_kyuji.dic.BAK"))
   (kyuji-to-shinji))
   ((t nil))))

(defun show-lub nil
  (interactive)
  (setq lub (list skk-large-jisyo skk-jisyo skk-backup-jisyo))
  (princ lub))

(global-set-key [f8] 'toggle-jitai)
(global-set-key (kbd "C-<f8>") 'show-lub)

結果

Emacs および DDSKK の起動時は旧字旧かなで入力できる．
F8 で旧字旧かなと新字新かなを toggle できる．
C-F8 で現在の状態を表示できる．