You can use Open Access with a custom modules which are not Generic Content based. We have samples with Sitefinity 4.0 and OA only that are available in the SDK installation. You can also take a look at the OA documentation for reference.
the Telerik team
Registration for Q1 2011 What’s New Webinar Week is now open. Mark your calendar for the week starting March 21st and book your seat
for a walk through all the exciting stuff we ship with the new release!