The headliner on a 240z is just glued to the roof pannel, and can be peeled off if you can get it started. Its hard to get out from under the chassis frame. The Liner on the frame however is a different matter. It cant be removed without taking out your front windscreen, as it is glued on under the window seal. After you take out the window, and door frame seals, you peel it away from the seal frame part toward the center of the car. Then when you look under the liner, there is a strip of plastic/metal edging stuff (like the stuff around the door frame) that holdes the liner in place. Why are you removing the liner? Are yo repainting the car? Might be easier to just mask the liner with tape and paper if you dont want to go to all this trouble.