Rear Center Plate Bird Modification
This is a general step-by-step way to perform this modificatio to your Firebird or Trans Am.
These are the 2 methods I have thougth of to achieve this modifiaction.  I have only performed
the first, so I am not sure as to it's results.  So the only one I know will work for sure is the first.
Method #1
Tools:
Procedure:
Exacto Knife
Electrical Tape or Hot-Glue
Wire Connectors
aluminum Foil
Ligts of some sort (LED or Christmas Lights)
Step 1:
Remove Tail Center Assembly
Step 2:
Clean the center plate up.  You will probably want to do this inside, or outside depending upon which method you use.  I don't suggest using paint remover inside the house hoever.  But definately method 1 in the house.  It's time consuming.
Step 3:
Here is where things get complicated.
Notice the bird is painted on and that the black paint is just a background for the bird and lettering which is painted on with another color.  In order to do this mod, you will just be removing the paint from the lettering or the bird emblem.  To do this, use the Exacto Knife to scratch the paint off that is under the black paint.  It will take a lot of concentration and reference from the front to the back to make sure you are keeping within the lines.  If you do mess up, you will be able to easily resolve the problems with some model paint on the small paintbrush.  You just need to touch up any misteaks that will be noticable in the end.
Step 4:
If you have got this far, you should have something resembling this when it is held up to the light.  Your next step is to clean the center up once again.
Step 5:
When you have made all error corections, and have cleaned the center up, you are onw ready for adding lights to your creation.  You can use whatever you want to, to attach the lights to the center assembly.  I thought of either Electrical Tape, or Hot-Glue.  I chose to use Electrical Tape and it has held up for about half a year so far through summer and winter conditions. 
Step 6:
Place the lights you have chosen in a format of your choice so that you will feel it will give the proper amount of light.  Remember:
More lights=brighter  Less lights=dimmer.
The brightness also depends how you wire them up.  I chose to wire them in a series so that I could get a certain brightness and used a large number of lights, yet do not need a resistor added.
Step 7:
After you get the lights wired up on the tail center, you can wire it up to a power source.  I just spliced the wires to some wires going to the tail lights, so that the bird would illuminate when the headlights or park lights were on.
Step 8:
After you have got that all wired up, you just need to form a piece of foil into a domed backing for the lights.
Be sure to make a hole for the lock.
The finished product also looks like it still has the silver paint on it. 
Step 9:
Re-assemble the tail assembly and stand back in amazement!
Method #2

Repeat steps 1-2
Step 3: 
Using paint remover, remove all the paint where the bird emblem and Ponitac lettering was.  You should              be left with the clear plastic.
Step 4: 
Using templates, put them on the plastic center and repaint with gloss black spray paint.  Peel the                       templates off, and you should be left with the same thing as in Step 4 of Method #1
Repeat steps 5-9
Finished Product Pictures
1