OpenOffice.org has support for various Accessibility aspects.
Keyboard navigation, scheming, AT support and much more. Details can be found here: http://ui.openoffice.org/accessibility/whitepaper.html.
If you want to find out if your AT works with OpenOffice.org, or how to configure OpenOffice.org to be used with an AT tool, you can have a look into http://wiki.services.openoffice.org/wiki/Accessibility.
There is a mailing list which can be used for user questions and
comments, as well as for developer related things. Please subscribe
email@example.com, or have a look into http://ui.openoffice.org/servlets/SummarizeList?listName=accessibility.
The OpenOffice.org Accessibility Project
More details about all Accessibility related things around OpenOffice.org can be found in the OpenOffice.org Accessibility Project and in the OpenOffice.org Wiki: