There is an access door below the light facing the ground. Pop it off and reach your hand up in and twist it out.
The fog light holes are roughly 3.5" in diameter if that helps at all. I am unfamiliar with the PIAAs that you mention, but they will most likely be heavier then the stock foggies. Mount them to the car and not the bumper cover if possible. The vibrations that the cover has will make your bulbs have a short life, plus the bouncing beam pattern would be annoying.
