My iphone 4 home button started misfiring about two months ago after daily use for two years. I had previously installed a new power and lock button from ifixit using their guide, so I was confident that I could go a few steps further. I watched the video first then went for it with the guide on a laptop at my bench.
The new home button works exactly as it should now! My only caveat would be that the screwdriver kits have a handle that is too thick, and cannot get a straight shot on the side mounted screws. I returned it and used a single tip driver. I would keep the kit if I did not have most of the tips in kits already.
I used two pieces of thin perforated shelf liner; one to lay the screws and parts in groups in their relative positions in the order of the steps, and the other as a work surface to catch any falling screw.