Remove the bushings, using either a skate tool or a wrench. Unscrew the bolt holding the bushings in place and slide them right off.
Heat up a pot of water on the stove. Place the bushings in the pot for 10 to 15 minutes. Turn off the heat and remove the bushings while they are still hot. Do not use your hands to pull them out of the water.
Reattach the bushings on the board while they are still hot. Simply screw them back on with the skate tool or wrench and the bolt. Start skating. You should notice a difference immediately. Riding the board right after you put them on will preserve the softness and allow them to loosen up even more.