I am considering doing the same thing. Love the hot nail suggestion for the screw holes. I found this guys site when I googled before finding this thread, just another example, and it has a link to the billet door on amazon, $20.
http://www.spyderrt.info/u-do-it
The text below is straight from 'Inspector Gadget' website. I intend to follow that pretty closely, with some slight changes suggested by BlueKnight911
---------------------------------------------------------------------------------------------------------------------
Fuel Door --- Price of Project <$80.00
Installing this Bully GD-301P Billet Aluminum Fuel Door was a bit of a challenge, but once I determined the exact location it worked out well.
1. After positioning it on the seat where indicated I used an Awl to punch holes where the bolts would go and then drill with a small (1/16") bit.
2. Then from the inside carefully drill 1/4" out through just the seat pan.
3. Now you can place the 1/8" aluminum backing ring that you have cut, drilled, and tapped to 1/4 X 20 and mark out for the pan cut out.
4. I used a demal with a wheel on it to cut the hole (see photo for size) in the seat pan and then cut the foam with a knife, being careful no to cut into the seat vinyl
5. Carefully cut the vinyl seat covering from the center making several pie shaped pieces, but do NOT cut all the way out to the hole edge, but just enough to make the vinyl roll over to the inside.
6. Using a stapler, pull the vinyl to the inside of the hole and fasten securely as shown in the photo.
7. Insert the bolts through the Fuel Door-through the seat pan, and now thread into the inside backing ring and tighten. Note the 1 long bolt and lock nut placement in the photo.
8. Made sure you cut the bolts just past flush with the backing ring so they will not protrude to far in or they will hit and scratch the tupperware when closing the seat.
Click on any photo to get a larger view. (Note from UtahPete go to his website
http://www.spyderrt.info/u-do-it for the pics....too much trouble trying to post them here)
Fuel Door Update: I really love the fuel door for its convenience and looks, but I found that the fuel door itself gets rather hot either from the engine heat or from the black color drawing in heat from the sun----so much so that at times it really burns the inside of my leg. Not wanting to give up my fuel door I fabricated a pot holder (for the lack of a better name) and it works very well. As you can see in the photos I can still access the fuel door by flipping the pot holder and placing it under the glove box lit. It is just slid in between the seat and tupperware and can be removed easily when I don't want it to be seen. It is covered with the same material that the seat is made from, but you could use just about anything to provide a different decoration as long as you use some batting material for the insulation. I used 4 layers of quilt batting.