paint scraper is the only way to go,
sandpaper will clog up bigtime, aa wire wheel will fling the stuff around over everything and id imagine a wire brush would be like pulling teeth.
i normally use the septone stripper from supercheap. if you put it on nice and thick and cover it with glad wrap, it will bust through layers upon layers of paint in one go.
another good trick is to use a razor blade and score the old paint with it. it allows the stripper to get a good penetration.