If it has the brake light switch built in you need to hold the piston centered while bleeding. If the piston shifts you will never get fluid to whatever side is blocked. You dont need a special tool, use a drill bit or any pokey thing that will fit in the hole. You should not get fluid when the switch is removed. If you do, the prop valve needs new o-rings.
You don't need any special tool, just bleed the brakes in the proper order and the piston will end up where it needs to be. Passenger rear, driver rear, passenger front, driver front. It's in the factory manual.