I'm not sure you even need the satellite lines connected. You probably need the phone line connected, though. You will probably need to comment out the "route" statements in your rc.sysinit.author in order for the phone call to go through. I don't know if the 6.2a update is still in the satellite stream, but it should be able to download it via phone.
Edit: Oh, to answer your question, I've always been able to get updates via phone on non-subbed boxes in the past. I would assume that's still possible.
Edit: Oh, to answer your question, I've always been able to get updates via phone on non-subbed boxes in the past. I would assume that's still possible.