Yes. It is preferable for a vet to do this, but it is fairly easy to learn. Many owners of megacolon cats do this routinely. If you give an enema, do not use human enema products. They can kill your cat.
There is a way to put a cat through that it would be like giving a human one just put it in the rear and then just squirt it in which would not feel good for the cat.
OK so what is different in a cat enema? Why would this kill the cat if vets are giving them too? I give human enemas all the time. This would just be a smaller enema LOL.
You would need to ask the vet that question, the vet would know more about that. You shouldn't give it one until you know for sure if it is safe for the cat.