Not hard at all.
All it takes is some vinyl wrap, hair dryer and a sharp blade.
You wedge the vinyl under the cover best you can then wrap over the buttons.
Use the heat gun to stretch the vinyl... it makes it way easier. After you have it all set use your blade and cut out.

You can find cheap vinyl on ebay, so if you mess up its no big deal.
You should be good w/ a 12"x12" roll ~5$.