Im assuming you have an E16, if so, its a rubber gasket, and i reused mine after cleaning it off. its best to replace it though. I'm sure you know this already but make sure your using a high-temp paint.
Hey rice rocket, I also have a GA16i and painted my valve cover. The gasket is made of rubber and very easy to replace. Bought the gasket from Canadian Tire. Here is a pic of my valve cover just to give you an idea.