It involves setting up two QT tanks. Basic concept is you put your infected fish in QT tank 1 with fresh saltwater. On the morning of their third day in that tank, you remove them to QT tank 2 which also has fresh saltwater. You clean and sterlize QT tank 1 and refill it with fresh saltwater. On the morning of day 3 in QT tank 2, you remove the fish back to QT tank 1 and clean QT tank 2. You'd repeat this procedure for a total of about 15 days which should complete the life cycle of any ich cysts that are in the tank/on the fish. So, it looks like this:
Day 1 - fish in QT.
Day 4 - in AM, but before tank lights come on (8-9 AM EST), transfer fish to new tank, matching temp and salinity. Transfer as little water as possible.
Day 7 - repeat.
Day 10 - repeat.
Day 13 - repeat and done.
Make sure you sterilize all equipment used between transfers or you'll recontaminate. Most advocate not using nets to transfer, use a container with as little water as you can manage to move the fish from tank to tank.