Best way to prep rallye wheels for paint?

If you do not have access to any of the equipment then you should use paint stripper. Let it set for a while, then pressure wash it off and scrub with steal wool or a wire brush. Then soak the rims underwater in a tub or something to ensure the neutralization of the chemicals, then rinse after you take the rims out of the water, let everything dry and then start the painting process.