Shovel any snow that is on top of the ice. Brush any leftover snow off the surface of the ice using a broom. Snow left on the surface of the ice will quickly refreeze, forcing you to re-melt these areas.
Plug the heat guns into a weather-proof extension cords. Start the heat guns and allow them to heat up for 10 minutes before using them.
Hold the heat guns about 1 foot above the asphalt. With your assistants, work in bands from one side of the driveway to the other. Sprinkle rock salt over the spots you have just melted. This prevents water from refreezing as well as keeping new ice from forming over top.
Turn off the heat guns and unplug them from the power supply when you are done. Place the guns in an open area with ample ventilation to allow them to cool off before storing them.