[OS X Emacs] How to make spelling correction work with French?

[Marc Shapiro -- at work]

Does anyone know how to make spelling correction for languages other than English work in Emacs on the Mac?

I am using Carbon Emacs sur MacOS "GNU Emacs 22.3.1 (i386-apple-darwin9.7.0, Carbon Version 1.6.0) of 2009-07-26 on gs674-seijiz.local". I do my spelling correction using flyspell-mode.

There is an interactive function for changing languages, and it offers French as one of its options:
	(ispell-change-dictionary "francais" nil)
but this brings up an error:
	Error in post-command-hook: (error Error: The file "/LOCAL/Applications/Emacs.app/Contents/Resources/lib/aspell-i386/francais" can not be opened for reading.)

Indeed this file does not exist.  At this location there are various files for English.

/sw/aspell running as an independent program has support for French.

I looked around the web. I found French dictionaries and instructions about adding a dictionary to aspell, but nothing that seemed relevant to Emacs on the Mac.