I found that out by accident. I don't know if it works for anyone else, or if it's just on my end, but it seems like when I use Firefox and am NOT logged into my account, I can still see channels with the old, still-barely-workable channels. It only seems to work on Firefox (maybe it also works on Chrome, but I don't want to get anywhere near it), as in IE I get the YouTube One (Person Thinks This Is A Good Idea) version regardless of whether or not I'm logged in.
Of course, feel free to try it out. Would be hilarious if it worked for everyone!