Okay you wanna know the secret to beta testing? You gotta be around a long time, stay in positive view by most of your peers while you are, prove trustworthiness, be an IRC visitor (thats the means of communication for large groups of people), and the one factor you cant control... you might have to wait for the other old people to leave cause theres no need for 1,000 beta testers.
Whats a long time? Probably a year and a half minimum (and not just a forum join time, you need to be an active member, in which people know your active). The exceptions to the time rule are the really friendly helpful ones are abnormally smart and knowledgable, examples being JonChappel and Vandalite.