Mossberg uses a one-way safety screw on their safeties. It is designed to be turned clockwise witha flat blade screwdriver. At the Mossberg armorer school, we are taught to use a small center punch to loosen the screw. Place the point of the center punch at an angle at the bottom of the slot of the screw head. You need to tap the center punch in an angle in order to rotate the screw in a counter clockwise direction. After the screw is loosen, you can use a regular flat blade screwdriver to remove the screw. Make sure you apply pressure on the safety button and the safety block inside the receiver before removing it. Their is a small metal plate, ball bearing and spring under it. You should disassemble the receiver by removing the the trigger assembly and bolt so you can have access to the safety block (silver L-shape metal block under the safety button, this is what the safety screw attaches to)
Release the pressure slowly so the parts dont go flying everywhere. Keep upward pressure on the safety block so the part does not fall out. Once the old safety button is removed, you can place the new one on top and screw it back in place. Brownells has an metal extended safety button with a raised center. I have it on my 590A1. Works great, even with gloves.