Currently a 4th level apprentice in Auto Body here, you really shouldn't do this yourself unless you have experience, but just incase you really want to... Here's what's involved: (Approximate time frame, 10-20 hours complete, depending on skill level)
Remove A, B, C Pillar trim.
Cut out front and rear windshield (using an air knife works best). Expect each glass to take between .5-1.5 hours, depending on how well your air knife works (you CAN do it with an Olfa knife, but expect it to take 2 hours or more, per glass). Then clean up remaining urethane adhesive with a razor blade (get rid of as much as possible)
Remove headliner (do it after the glass unless you can shimmy it out the back of the wagon, in most sedans this is not an option, but it might be for you).
Remove moon roof. Probably about 8 10mm bolts and a couple drainage hoses.
Remove roof mouldings/roof rack, and mask off your roof rails and windows.
Look for resistance spot welds, they will be approximately 1/4" in diameter, and probably spaced out every 6 inches or so. Drill them out with a spot weld cutter. Then use a seam-buster to crack the panel bond between the roof skin and roof opening flange (you can use a chisel if you don't have one or can't find one, but you don't want to damage the roof flange).
Remove roof skin, use a 3M (or whatever you want) abrasive wheel to remove existing adhesive and clean it down to bare metal.
Test fit the new roof skin. Make sure it actually fits. Mark where it will sit in relation to everything else.
Sand down the E-coat on the joining surface of the roof skin. Use 3M Panel bond on both the joining surface of the roof skin and the roof opening flange, apply a thin even coat to the whole surface.
Lay the new roof skin in place.
Resistance spot weld the front and back of roof skin (through the adhesive). This is where you run into problems because these machines are EXPENSIVE. Like, anywhere from $5000-50,000. Maybe there's cheap ones out there, but a quick google search didn't yield anything for me.
Seam seal the edges at the joint, allow to dry, they paint roof.
Reinstall front and rear windshields. Check for leaks.
Keep in mind, some roof skins need to be welded at the sides as well, and I didn't look up the specific procedure for your car, just gave you a general overview of whats involved, to try to deter you from doing it yourself. It's a lot of work, even for someone who knows what they're doing and has the equipment. Also keep in mind that on a unibody vehicle, the roof is a structural piece, along with the windshield, and if installed wrong, serious injury or death may occur (not my fault, I'm telling you not to do this).
In all honesty, just take it to a body shop. Take out your interior to save yourself a little money, and MAYBE do your glass (it might break, and then YOU have to pay for new glass, but if they break it, they do). Regardless, you'll still have to get it painted unless you do it yourself, and if you were going to do that (much safer), get them to do the roof skin and paint it yourself, and save yourself some money that way.
Hope this helps, and keep in mind, GENERAL install instructions, this is a guideline, not a how-to.