If you have a shower with a door there is a gentler way to bathe your cat. Bring the cat, two buckets of warm water, a sponge and a bottle of cat shampoo into the shower and shut the door. DO NOT TURN ON THE SHOWER. Sit down on the floor and give the cat a minute to explore. Dip the sponge in bucket, wring it out well and use it to stroke the cat. Continue, allowing the spong to get a little wetter each time until the cat has also gotten thoroughly wet. As long as the cat is being stroked and not held down, they are usually fine with getting wet. Put shampoo on your hands and stroke them all over. Once they are shampooed, use the sponge and the second bucket of water to rinse the cat by dipping the spong in the water and running it over the cat.
This method takes longer because you need to take time to wet and rinse the cat, but is far less traumatic on the cat and they really don't object or get too upset so long as you don't try to pour water on them or hold them down. I've used it a number of times with older cats with grooming/back end issues and it works wonderfully.
