Jon, I don't know if this is the kind you are looking for, but we install epoxy flooring, and I called the makers of the material to find out what I could to to make it non skid. They told me to get aluminum oxide like is used to make sandpaper and broadcast it onto the sealer before it dries. I couldn't find any aluminum oxide, so I bought some bead blasting media in a five gallon bucket from Grainger. It was like $30/bucket. I bought the fine stuff so it wouldn't sand peoples feet off. I imagine you could do the same with gel. Broadcast more than you think you need, because about half of it won't stick.