Not 100% sure if they are actually rivits but thats what I call them
There are two metal rivits that are under the sail window. One on each side. If you are really good you can snap those out without breaking the sail window, but is very hard to do. You are better off to take the sail window off and then you will have access to the rivets. They are located about 1 inch over from the door, and 1 inch up from the bottom of the sail window.
As far as the piece that the engine vents hook onto, there are some screws on that. Once all the screws are out it does just pop out. Easier to pull it off by using a small flat head screw driver and starting by the rear window and working your way down.
**You are best if you do Step 2 first. Then you can take a razor or knife and cut the sail windows out. If you have a heat gun you can heat up the edges some and the tape holding it will come off. There are also supposed to be string inside the tape that you can pull to get the sail window out, but only 1 of mine had the string.**
You also have to make sure that both fenders are off on the rear.
Also the tail lights have to be out as there are screws behind those.
Another thing you need to do is the gas cap housing needs to come off.
After that it should be free. Dont forget even thoe you took the screws off inside the car on the headliner that you need to pull up on the roof section itself as the fastback clip lays under that. Be carefull pulling the roof up so you dont break it.
That is basically it. If you need more help let me know as I just got done takeing two Fieros apart. Very easy to do.