Purchase a faucet adapter and a backflow preventer vacuum breaker (for hoses) at the hardware store. The adapter changes the width of your faucet nozzle so it can accept the hose, and the breaker ensures that your water supply does not get tainted in the event the water backs up while in use. Some faucets may already come equipped with a backflow preventer--check with your manufacturer.
Remove the faucet tip by unscrewing it slowly counterclockwise, retaining the rubber washer and screen housed within the tip. Use a small wrench if it is tight; sometimes calcium buildup makes these difficult to unscrew by hand. Store parts in a baggie for safekeeping.
Attach the faucet adapter by screwing it on by hand in a clockwise rotation. Screw in firmly but do not over-tighten. Turn on the water to make sure the adaptor is properly seated before attaching the hose.
Attach the backflow preventer onto the hose before connecting it to the sink. Then attach the hose unit to the faucet, screwing it on in a clockwise motion. Turn the water on slowly to test that you have a good seal on it before operating at full throttle.
Reverse directions when returning the faucet to regular use. Apply Teflon plumber’s tape to the thread on the faucet tip before replacing, in order to prevent dripping.