Maybe have an artist or song of the week for RBN, and promote it during the DLC announcements on Friday or something? Post it on Facebook and Twitter...doesn't necessarily have to be an artist or song released that week from RBN. The Friday announcement time seems to be when most eyes are focused on Harmonix goings on, so that would appear to be the best time to do it. Maybe like an hour/hour hour before the DLC announcement?
Maybe the song or artist of the week will hold more weight coming from Harmonix proper? I know Fairwood has done one a day, and we've promoted our past material, but it hasn't had a whole lot of effect. But again that might change if it's coming from Harmonix.