Going by the numbers in the article, ~48% of all voters don’t like either candidate. That puts the ratio of people who like their candidate to the people who don’t like either at about the same as the Republican/Democrat split. If everyone voted for a candidate they actually like right now (assuming they find a third party they like), there’s a chance it could happen this year. Even if it doesn’t, 48% of people voting for a third party would show everyone else that it’s a viable option.
If you wanted to take a look at the manual, you might have luck finding it on manualslib.