Roland's blog

For a little while I couldn't figure out why a dictionary wasn't installed with OpenOffice in Gentoo. If you install a bunch of software at the same time you will miss the portage message which says:

* openoffice-bin does not provide integration with system spell
* dictionaries. Please install them manually through the Extensions
* Manager (Tools > Extensions Manager) or use the source based
* package instead.
*
* Dictionaries for english, french and spanish are provided in
* /usr/lib/openoffice/share/extension/install
* Other dictionaries can be found at Suns extension site.

So What you need to do is this. Add in /etc/make.conf (or just en if you want only the English language)
LINGUAS="en en_GB es fr"

Emerge aspell-* or myspell-*.

Emerge openoffice-bin (or openoffice if you want to compile the whole thing) and run "ooffice".
When the app loads go to the "Tools" tab and then "Extension Manager". Browse to /usr/lib/openoffice/share/extension/install and add the dictionaries.