empeg picks their alpha testers by hand, there has never been an official "sign-up" procedure. Their beta testers on the other hand is anyone willing to download and install it. Right now the alpha testers see the potential public betas for a few days to ensure there is nothing major that occurs, like the upgrade simply not installing, or other issues. But before 2.0 went into public beta, they got to work with a few versions of 1.1 that were definitly alpha quality.