I have had really great luck with the West Marine non skid paint. I don't think regular topside paint will give enough traction, especially when wet. One thing, if you buy nonskid paint, just get enough, don't buy a whole gallon even though it seems economical. The nonskid material will skin over in the can over time and you wont be able to break it up into the small particles (don't ask me how I know this).
Manny