How I did it: It was really hard to do and I would not recommend doing it by yourself. It took me a long time to cut it out right and to measure it. It was tough to reach so I had a chair to stand on. It was a VERY messy process as well. I bought the pre-pated kind but the soaking and the unfolding got paste all over my floors.
Lessons & tips: Bribe a friend to help you
Resources: get the prepasted stuff and measure twice before you cut it.