For male breasts to start producing milk the male must take a HIGH dose of one of the female hormones (I can't remember which one it is) and a medium dose of several others. He must continue to take it throughout the breast feeding.
He must effectively become a pre-op transexual. He will have breasts for the rest of his life.
Males do on occaision produce liquid from the nipples: It is a sign of an infection or breast cancer.