So is this just a six pack scoop to be mounted on a steel hood? Or a whole fiberglass hood with integrated scoop? To cut the scoop holes just punch a whole near the edge then use an air saw, roto zip, or Dremel to trim them out. Any will do the job. Then file and sand the edges till yer happy with em. If the scoop is to be mounted on the hood sometimes they have tabs inside to mount with hardware (nuts & bolts) but the nicest way is to use fiberglass to graft it in/on to the hood.
I've seen guys that used bondo to graft them on but it looks cruddy IMO and mounting it with hardware leaves a noticeable gap between the scoop and the hood. Grafting with finger glass is the best way to mold it in so it looks seamless I think.