We do it using the IEAK. That way you can customize it with everything that you need and the settings you desire. From there, the users pull it via batch files (no SMS yet, GPO not possible because are not in native mode yet).
String together any patches you need after the install. Granted 800 people installing at once isn't ideal, so break it down somehow that is fitting to your agency. We've got ~3500 users, with the package replicated to 6 other regional servers other than the central office. Matt