If anyone needs to remove their sunshade to re-upholster or etc on their 2000+ Bonneville, below is the proper way to do so:
1) Open sunroof to the "vent" position
2) Remove the two torx screws that hold down the cross bar that operates the sunshade. You'll see them in each corner under the glass.
3) Slide that cross bar out from under the glass roof.
Now open the sunroof completely, then slide the sunshade out from under the "catches" at the front of the glass, then open the 2 tabs on each side of the sunshade and remove out the top of the car.
Leave that cross bar out until you have the shade reinstalled.
I searched and read stories saying you had to remove the headliner or remove the entire sunroof! After a long time trying to get the sunscreen to go back in, I realized the proper way to remove and install was to simply remove that bar! FYI