I did it in my '91, you gotta take all the front trim off, then take the walls loose, or take em out completly, take the lights down, then carefully try to take those plastic retainers out of the middle of the headliner, good luck with that. then the sides are held in place with the plastic wing looking retainers, those can be turned till they are out of the way. Now if you dont have a sunroof, you should be able to take the whole thing loose, if you do have a sunroof, you will have to carefully pry back the rubber weatherstripping around the opening, then it will comeout.
I think it is lipped on the front edge, meaning you will need to push the whole headliner forward a little then pull down.
Whatever you do, dont force anything, that shell is brittle as hell, and once you crack it the cracks will show up through the new material.
If yours is kinda tore up or nasty, recovering it makes a big difference. You will get the laminated foam headliner material, right?