I remember taking the material off the seat back to change a tilt lever cable, and I didnt actually take the cover right off, as there are wires fitted to the cover to pull it into shape over the cushions and keep the tight profile/shape. So you need to fiddle with these to detatch them, and I imagine the base is similar.
So you may end up with a bit of butchery in getting the covers off, and would need to ensure the wires were relocated on refitting to ensure the fabric sits propoerly, rather than being loose and wrinkled.
That said, its not quantum mechanics. It has been done by many before. It just may be a fiddle to get a good finish!