If you get the ones that only require that you drill 2 round holes (attwood neat cleats).... Can't be that hard. Some of them don't even require that you're able to access the bottom side.
If you're like me (cheap... and dumb) you'll buy the ones that you need to cut a perfectly shaped hole without any kind of template. It's dremel hell. And then you have to play stretch armstrong to reach under the bottom side to tighten them up.