Quite easy. Take four screws off the trim piece. It has vertical ribs that stick up about an inch and a half. It might be stuck against the ceiling material, but the four screws are all that hold it to the ceiling. The wiring will be wrapped around the edge of the fan. There should be four more screws that hold the motor/fan assembly to the top flange. You will also have to remove the turn up knob (Phillips screw in the middle) and the speed control knob (pulls off) You will probably have to cut the wires and re-connect to new part leads.
Your parts should come with a diagram. Fantastic is a pretty good product.
Al & Sue w/T-Bone & Rosco
Go Devils Bus, 1994 8.3 Cummins, Spartan Chassis