How do we prepare a painted concrete patio floor for tiling?

I think you have to get rid of the paint by waterblast, sandblast, grinding or any other means so that tile adhesive can bond with the concrete. The only other method I can think of would be to attach concrete backer board to the concrete with screws and that would definitely jack up the cost and duration of the project by 50% or more, if it can even be done.