1. Start by roughening the tiles slightly, either with a paint deglossing liquid (available at paint specialty stores), or by sanding with a 120-grit abrasive in a random orbit sander. The idea is to take off any smooth shine that might interfere with paint adhesion.
2. Next, clean the surface thoroughly with a vacuum, then wipe it down with more methyl hydrate.
3. You’ll need to start painting with an epoxy primer. This is a two-part product that cures by chemical reaction after it’s mixed.
4. After this primer is hard, add a couple of coats of epoxy paint.
5. Let the whole thing cure for at least a week, then enjoy your floor.

The coating won’t be nearly as tough as ceramics alone, but it should be pretty good. Just don’t drag anything across the surface.