You don't have to pull the hubs to change U's. I've done it more than once pulling out the whole thing with hub attached. If you dont have ujoint tools to change em plan on trashing an old socket or 2. Use a BFH to pound em out. With a little practice, you can do both sides in an hour. You have to pound em out in stages. 1 side half way out, remove the cap, go back the other way remove the cap. It'll then come out. Install in reverse. Big metal vice helps hold things. Protect the splines on the ends of the axles from dings. When reinstalling make sure you don't puch gook from inside the axle housing into the pumpkin. It can get pretty nasty. Clean em out if possible and be very careful when reinserting into the inner seal.
PM me if you have some specific questions. I've prolly done this 10 times on 3 XJ's already.