Purchase a few pairs of pantyhose. If you have old ones lying around without holes, use those.
Fill each leg of the pantyhose with calcium chloride pellets. For best results, tie each leg off every 6 inches, creating multiple compartments of calcium chloride pellets. This allows the device to be more effective, preventing the pellets from gathering together in the foot.
Repeat the process so you have enough to cover your roof, with an ice melter placed every 4 to 5 feet.
Grab a ladder and place the pantyhose across your roof so one foot hangs slightly off the edge, over the gutter. The legs of the pantyhose should be 180 degrees apart, perpendicular to the ridge of the roof. Once placed, the calcium chloride begins to melt the ice and snow from your roof.