The Rock Band Blitz demo was distributed as a roamable package -- i.e. no license that ties it to any particular console (this was intended for e.g. demos distributed on magazine CDs or whatever).

You can just throw it on the filesystem and the console will accept it. I believe it would require a system update to add the executable to a revocation list, which Microsoft is unlikely to do. It's not the only method of achieving initial code execution either.

There's now an entry method that just uses a profile/avatar, so that's not even needed. You just boot the console with a USB stick containing the payload, and you're off to the races.

I just started digging into hacking 360s this week, and I'm blown away by how simple it is once you cobble together some files from a few github repos...