Both of your links are the same (no ref to 'Forbidden' that I saw on that page). How many rows of each color are you planning to do? You can carry the unused yarn up inside the hat while working with the other. You need to be concerned about your color 'stepping' as you switch so look into jogless joins (existing posts on this topic on KH). Otherwise, it's pretty straight forward. Instead of working with one color you'll still follow the patt but every so many rounds will switch your color.