First off I wouldn't do it with the switches installed. Chances are it is just going to make a mess as it will be about impossible to mask off the switches. If your are really looking for a painted plate and are looking to change switches anyway, I would just pony up the cash for a decent iron and a Soldapult from Edsyn. Remove the switches, paint, and reassemble.
For painting the plate I would recommend a quality spray paint and primer. I don't actually know much about spray paints to really recommend any in particular though.