A few posts down is something about someone who just got a duster and i wrote some instructions, but since I'm lazy here's a cut and paste of it..
I don't have a duster, but I take my Soft-Top off quite a bit. First you take out all the windows including the rear (or roll it up). Then you pull down on the tension elbows in the middle of the rear quarter windows (the bar that goes parrallel with the body of the jeep) and get some slack in the top. The lip of the top that hooks into the windshield can be pulled free now. In addition, at the corners of the windshield are little plastic latches that say lock/unlock, put those to the unlock position and pull outwards on the soft top frame to release it from the body of the jeep. After that the entire thing can slide off the jeep (it's on runners. If you want to take just the canvas off, you can just undo all the snaps (about 20 of them) and it comes right off. That's how it works on my '95 YJ atleast.