I would probably vote for Lieberman, but McCain could persuade me to change my mind. (Explaining why he endorsed Bush in 2004 would go a long way.)
McCain would win with at least 500 electoral votes, as his insurgent image would fire up moderates, Perot voters, and people who don't normally vote. He'd get the votes of some liberals from the Democratic coalition.
I just don't understand the appeal of Lieberman. He kisses up to Bush too much, which confounds me considering that he represents Connecticut, not Kentucky or Idaho. Also, I can't see how Lieberman fires up anyone of any ideology. Correct me if I'm wrong, but I highly doubt that moderates, independents, and other swing voter groups vote have a 50-point checklist on where the candidate stands compared to their views. Even if they do, these voters would have to choose between one set of issues and another, so the hot-button issues would be a wash for them. Can someone enlighten me on why people would be fired up about Lieberman? I can tell you that at dailykos.com and mydd.com, Zell Miller is the only less popular Democrat.
I think that's an underestimation of Lieberman. He would actually do pretty well.