I took my cardboard on out without the glass out.. AFA glass out, theres these damn little pointy shards of metal that the material headliner attaches to . I'm pretty sure that it cant be done. I am pretty sure it would make attaching the material impossible.. I have always had glass out, and been lucky.
I haven't reinstalled the cardboard, but I THINK it slips under the window gasket, side trim, sails.
Will take a better look - brain fart
Grant