Open Hypspec with w3m

[Jason Earl]

I have been spending a bit of my free time learning Common Lisp (and
enjoying it).  Part of learning Common Lisp is getting to know the
HyperSpec.  The fact that Emacs includes a function 'hyperspec-lookup
that makes this a matter of a few keystrokes is very helpful.  However,
by default this opens up the page in Firefox, and I would pretty much
always like to open the HyperSpec in w3m.  I would change the default
browse-url-browser-function, but I generally want to open URLs with
Firefox.

For Common Lisp buffers I make 'browse-url-browser-function a local
variable and set it to 'w3m-browse-url.

--8<---------------cut here---------------start------------->8---
(add-hook 'lisp-mode-hook 'jadoea-lispstuff)

;; my python configuration
(defun jadoea-lispstuff ()
  "Custom Lisp Configurator.

Turn on flyspell-prog-mode.  Clean up whitespace on save (leave
tabs).  Make browse-url-browser-function buffer-local and set it
to browse-url-w3m."
  (flyspell-prog-mode)
  (add-hook 'before-save-hook
            (lambda ()
              (jadoea-clean-whitespace t nil)) nil t)
  (make-local-variable 'browse-url-browser-function)
  (setq browse-url-browser-function 'w3m-browse-url))
--8<---------------cut here---------------end--------------->8---

This works great as long as I am in a Common Lisp buffer, but I find
myself constant wanting to look up stuff from the HyperSpec while in a
Slime REPL, or some other type of buffer.

So is there a way to override 'hyperspec-lookup so that it always
behaves as if browse-url-browser-function was 'w3m-browse-url?

I build Emacs from source, and I maintain my own branch so that I can
easily deploy Emacs on various machines.  So I considered simply hacking
common-lisp-hyperspec to do what I wanted.  However, that hardly seems
like the cleanest way to do this sort of thing.

Any suggestions?

Thanks,
Jason