Any fine tooth hole saw from the local hardware store should put a hole in it. They sell hole saws specifically for drilling into metal. Plus make sure your pilot bit can actually burrow through the metal, too. If your pilot bit can't dent it then you'll never get down to the saw to cut it.
If your pilot bit keeps running around on the surface before going in you may want to start with a smaller starter hole using a standard metal bit. Make something like a 1/8 inch hole. That way you're sure it's centered.