Museum members get priority, but GA tickets are available at the box office starting at 6:30pm on a first-come first-serve basis. Movie is at 7:30pm. Q&A after movie at 9pm. (Apparently, they’re livestreaming the Q&A at the link above, but it may not be as relevant without seeing the movie first.)
There’s also a fundraising screening next month: http://www.ccapinc.org/locations/los-angeles/2008/08/events-4/ (ignore the fact that the URL says 2008 for some odd reason.)