2006 TRD Hood insert replacement.

I recently purchased a OEM Toyota hood scoop insert since I didn't want to bother repainting my weathered silver one with some paint that might end up peeling off from some store paint rubber coated paint. You may know this product I got from Amazon and it comes in variety of colors.
It got pretty good reviews. At first was going to get the black but it came glossy and matt black would have looked better as a contrast to my silver Taco. I haven't open the package yet but I saw a thread on this where you remove some bolts under the hood, then there is this center screw as well. What I don't understand the rivets that come in the packet. I don't have a rivet gun. What would they be for the black plastic center piece in the scoop opening? Also should there be some sort of seal or weather stripping for the insert?