Look for a RCN center close to you. They can swap your converter for a HD box in the RCN offices. RCN offices don't have TiVo boxes though. A tech is required to install any TiVo box.
I will definitely visit the nearest office to me, as it's hard to believe there are no other HD boxes other than Tivo's. Too bad I can't get a Premiere though, It shouldn't be hard to connect an extra one as I already have the line and the bundle.