Make official announcements and AMAs on non-Riot sites like Reddit instead of your actual forums. (I found out about them from going to Reign of Gaming.)
Pendragon (amongst others) already commented a few times bout this. Basically, they won't sollicitate the movement of the players toward the community until they are happy with its content/flow. In short, as long as it's a Beta community, you won't see anything major in here unless the creator chose by himself to do it. (ie. Community team did an AMA in ehre, Ironstylus chose to drop by and post a bit, without anyone asking him).
Converse about Community Beta, not on the actual Community Beta, but in an on-game chatroom. (Isn't that what this Community BETA is for anyways?)
While the community offers a great platform for communication, don't be that guy. Of course an async platform can't help you chat better than a chat platform. Also, where is the harm in using one of Riot's system to discuss about one of Riot's system?