Select a location for the trap. Try to put in a place where cats don't usually go. Raccoons tend to be more brazen than cats, and they don't fear things such as water or dogs the way that cats do.
Bait the trap. Choose a bait that will attract raccoons but not cats. An ear of corn is a great choice, as raccoons love corn, while cats won't be enticed. Raccoons also are fond of marshmallows, which cats typically aren't interested in.
Put out a deterrent to keep away cats but not raccoons. You can purchase cat repellent powder and spread it around the radius of the trap. Mothballs also deter cats, as does anything with the scent of citrus.
Set the trap at night. This is when raccoons are active. Keep your cats locked inside while the trap is set.