I would search for it to get the details, but basic idea is that you put a pice of raw shrimp in a bottle and let it ripen throughout the day. Put a cone lid on the bottle (like a fruit fly trap) and put it in the tank at night--cirolanids go into bottle for the shrimp and stay in the bottle.
Caveat is that some people say the cirolanids can get out. So others have tried just using the water from the trap, suck it up with a turkey baster and slowly spray it against the glass--cirolanids head for the glass and you suck them up with the turkey baster and discard.
All of this happens at night, so not a bad idea to have a red flashlight or if you have an LED with red channel just turn the red up at night.