Use the following at your own risk:

I believe the version you are looking for was previously in extras or extras-devel, but was removed to prevent it conflicting with the newer hildonized version. I did search on gronmayer.com/it for abiword and seem to have found a similar version (possibly the same one). Without further ado, here's some instructions to try if you're really hell bent on installing this version of abiword:

Applications Menu -> Settings -> Application Manager. Then open the menu in Application Manager: Tools -> Application Catalog. Click 'New' and make the following repository:
Catalog name: abiword
Web address: http://rickybrent.com/maemo/debs
Distribution: chinook
Components: free non-free

Now find your 'Maemo Extras' repository entry and click 'Edit.' Make sure it looks like this:
Catalog name: maemo Extras
Web address: http://repository.maemo.org/extras
Distribution: chinook diablo
Components: free non-free

Now, let it update the list, then click 'Browse installable applications' and find Abiword. Try installing it. I believe it should install fine, but I didn't have enough space on my N800 to try it. Tell us how it works out.

-John