Sorry, i misunderstood your question.
Anyway, a majority of people put a new layer or color fill layer with a black mask for each color below the artwork and use the brush and/or pencil tool to to color it.
It seems like using the magic wand and fill or paint bucket is hit or miss, no matter the version photoshop, because of the anti-alias involved, that either in the brush strokes or the selection produces.
