Iceape mail British English dictionary

On Debian Lenny AMD64, Iceape mail checks spelling with English/United States with no option for British English even if you've installed the en_GB package. The language pack on the web doesn't take properly. This is how to fix it.

1. Run mozilla as root
2. Install the dictionary from https://addons.mozilla.org/en-US/seamonkey/addon/3366
3. Fix the directory permission with chmod o+r /usr/lib/iceape/dictionaries/*

Update: the bug was reported and is due to be fixed (but report #499443). .