Set up between the roost area and their usual direction of travel, off to the side of your best guess of their path.
Wait until you hear a soft tree call or two, then respond with the same. Don't overcall and try to drown them out at the first calls you hear. If you can get the hens to "talk back" to you, follow their lead and make the same calls they do. Let them do most of the calling. They're the pros.
Like someone posted, try to get the hens to hunt for you.