So you can put one in without taking the windows out, however it is a pain because of the little teeth that grab the headliner front and back. It is really easy to do though.
additionally you need to have the a pillar trim and all the upper door frame seals completely out as well...
1) lay it out in the sun to warm it and smooth out the wrinkles/folds. Also find the cent front and back and mark with a chalk mark (tailors chalk is best, usually from a fabric store, Michaels, Hobby Lobby...whatever you have
1a) You may have to use a heat gun for stubborn wrinkles....
2) I always put the screws in there holes to be able to locate them through the headline once it is in. It is way easier to feel a screw than to try and feel the hole the screw goes into!
3) This is a good time to make sure your insulation/sound deadener is good to go!
4) lay out the bows and just cut through the sheath that the bows go through (keep bows in correct order!!!)
5) Place in car (usually from back to front) hook the tension spring/hook then work your way the other direction and hook over the "teeth" in the window channel. You will work forward and smooth and pull (lightly) ensuring it is aligner left and right
6) Double-check your side to side alignment and eveness
7) ensure the "slack" is pulled out front and back. This may be a slow process, be careful and just take your time, it is a really really good idea to have a heat gun handy to smooth out stubborn corners, and compound curves.
6) Once you have all of that done you are ready for the sides. I use the trim adhesive that comes in a tube and the small lime green spring clamps that you can get from Home Depot. Good quality clothes pins work okay to.
7) You will need to start in the center of the door frame between those two bows and pull the material (helps to do both sides with a helper to ensure it is pulled evenly) then glue and clamp as you go. Move to the next area between the bows (both sides again) and continue this until you have it glues and clamped....
You will also have to make sure that the material is spray glued to the sail panels...if yours are bad/broken you will have to make some out of heavy upholstery board (cardboard..)
let me know if this helps. I may be able to get some picks since I am getting ready to do another 66 Cuda soon...
randy