Lift off as much of the old "gunk" as possible using something like a plastic knife, etc. The, make sure that any filmsor tape like materials are also removed. Then use rubbing alchol and Q-tips gently "scrub" both surfaces until they are very very clean to the eye. After that "buff" both surfaces with some sort of "lint free" material. I use coffee filters because they seemed to work for me.
As for the AS5 application -- just "poop" a bit onto the CPU. This "bit" should be about the size of a medium piece of rice (or mouse terd - it you know what that is). Then reassemble - with a bit of a "twist" and you should be good to go - that is if the amount of AS5 used is OK and there are no air pockets. You may have to do this a couple of times before you get it "just right" - no telling until after you completed everything and run it for a few hours/days.