Whether or not you can pull a diaper up and down depends on your body shape. I find it quite easy now, but when I was younger and skinnier I couldn't do it at all. Having a bit of a belly turns out to be convenient!
I put on diapers exactly as @Draconic describes by leaning against a wall. With a bit of practice, it takes about a minute to tape one up and get it adjusted. It may seem daunting at first, but it does get easier.