On all the interior screws I've painted, I just took a piece of cardboard, punched a bunch of holes, stuck the screws through, and sprayed the heads. After installation, if any touchup was needed, then I got out the artists brush and dabbed a little paint on. It makes for a more uniform finish and you don't have to try and brush the whole screw, usually just end up touching up where the driver contacts it.
Bob
