Does the following version of my patch look OK?  If nobody ever would
want to change `lao-key-alist', one could use something more along the
lines of what Stefan suggested.  However, the current defconst's are
misleading and generate compiler warnings, so _some_ kind of change
seems necessary.

===File ~/lao-latest-diff===================================
*** lao.el	01 Sep 2003 16:08:19 -0500	1.8
--- lao.el	22 Nov 2004 19:48:41 -0600	
***************
*** 2,7 ****
--- 2,8 ----
  
  ;; Copyright (C) 1997 Electrotechnical Laboratory, JAPAN.
  ;; Licensed to the Free Software Foundation.
+ ;; Copyright (C) 2004 Free Software Foundation.
  
  ;; Keywords: multilingual, input method, Lao
  
***************
*** 42,48 ****
  	  (compose-string (quail-lookup-map-and-concat quail-current-key))))
    control-flag)
  
! (defconst lao-key-alist
    '(("!" . "1")
      ("\"" . "=")
      ("#" . "3")
--- 43,51 ----
  	  (compose-string (quail-lookup-map-and-concat quail-current-key))))
    control-flag)
  
! ;; If you change the value of this variable while lao is already loaded,
! ;; you need to re-load it to properly re-initialize related alists.
! (defvar lao-key-alist
    '(("!" . "1")
      ("\"" . "=")
      ("#" . "3")
***************
*** 148,159 ****
      ("\\9" . "໙")
      ))
  
! (defconst lao-consonant-key-alist nil)
! (defconst lao-semivowel-key-alist nil)
! (defconst lao-vowel-key-alist nil)
! (defconst lao-voweltone-key-alist nil)
! (defconst lao-tone-key-alist nil)
! (defconst lao-other-key-alist nil)
  
  (let ((tail lao-key-alist)
        elt phonetic-type)
--- 151,170 ----
      ("\\9" . "໙")
      ))
  
! (defvar lao-consonant-key-alist nil)
! (defvar lao-semivowel-key-alist nil)
! (defvar lao-vowel-key-alist nil)
! (defvar lao-voweltone-key-alist nil)
! (defvar lao-tone-key-alist nil)
! (defvar lao-other-key-alist nil)
! 
! ;; These need to be re-initialized if lao is re-loaded.
! (setq lao-consonant-key-alist nil
!       lao-semivowel-key-alist nil
!       lao-vowel-key-alist nil
!       lao-voweltone-key-alist nil
!       lao-tone-key-alist nil
!       lao-other-key-alist nil)
  
  (let ((tail lao-key-alist)
        elt phonetic-type)
***************
*** 197,201 ****
--- 208,214 ----
      (v-state (lao-vowel-key-alist . t-state))
      (t-state lao-tone-key-alist))))
  
+ (provide 'lao)
+ 
  ;;; arch-tag: 23863a30-a8bf-402c-b7ce-c517a7aa8570
  ;;; lao.el ends here
============================================================
 LocalWords:  diff