well if you want to do a nice job of it, your going to need to spend a bit of time.
-firstly get some "scotchbrite", its made by 3m and its a great way to prep plastic
-pull your controller and ps3 case apart and rub the plastic with the scotchbrite, until theres no 'shine' coming off it (hold it up in the light, it should be like a matte finish)
-mask it up or whatever youre going to do
-either spray it with spraycans (not as good of a finish) or find a cheap airbrush that you can use
- do 2~3 coats (letting it dry inbetween)
-let it sit for atleast 24 hours before puting it back together
also this is obviously the long way of doing it, but if youre going to do it you may aswell do it right =D