Take this for what it's worth as I don't have a sunroof or side airbags, but I have dropped the headlinner a couple times and it is prety strait forward.
Start by removing the trim from the A pillers. There is a screw behind the plug at the top. Pry the plug out and remove the screw the pannal is then held on by friction clips and can just be pulled off.
Use a TORX bit to remove the top seatbelt mounts. I think it's either a T40 or T45. Pull back the door seals and again, it's just held on by friction clips. I think there is a clip that is on the bottom panel that goes through the top one. Be mindful of this so you don't break it.
The one around the back windows is a pain because it is big, but as I recall, it is only held on by friction clips. Pull loose the rear door seal.
Remove the rear view mirror. Unplug the harness on the back of the mirror. There is a small screw that holds it in place on the windshild mount. Remove the screw and the mirror slides up and off.
Remove the sun visors and the inside clips. You can then unplug the onstar mic (and I'm guessing the sunroof switch and map lights).
Rmove the dome lights and unplug them.
Remove the grab handles. There is a screw behind the plugs on each end.
Remove the christmas tree pins in the headlinner.
The key is to remove everything that is going to be in the way as the headliner comes down. You may want a friend to help as you get further along in the process to suport the headliner so it dosen't bend. It is prety sturdy, but a bend would be bad.