Monica, I just went through the whole CC to LS deal about a month ago with my 55 gal. I cant say this is the best way to go but its the way I went. I bought two 30 gal rubbermaid containers and a small submersible pump from home depot. The containers were from the dollar store for like 8 bucks a piece and the pump was no more than 20 dollars. I pumped the water into the containers, mounted my heater in one to keep the fish in. Next I caught and moved all of my fish after all the insides of the tank were removed. I finished pumping to within about 1-2 inches of the bottom. I then removed the UGF and CC and pumped out the rest of the water.
I then began adding my 45lbs of aragonite topped with 45 lbs of LS. I refilled the tank with water until I could start my filters and let them clear the water. I added the fish and topped off the rest of the tank and was done.
It took about a night to complete, but was no big hassle. I talked to my LFS about it and his answer was that there was just no really simple way to do it but to break down the whole tank.
Hope this will help! Keep us posted.