I used stove ash mixed with a little Sevin dust. I employed this technique--fill a wide, shallow bucket half full w/stove ash, stick them in a feet first or on their back (either way they're not going to like it) then wearing gloves, scoop up the ash and smoosh it up under each wing, the vent, rub some into the chest, belly, neck and back. Put chicken back on the roost and grab the next victim.
Ooh, I want some chicken swings too! I've just fenced in a small area under the apple trees off the run (the playground) but need to put up some bird netting or deer fence since the smart ones have learned how to fly over out of it but not back in. Did DH use rope or chains for the swings?
The problem w/this is you are also covered in stove ash. I should have worn a dust mask & goggles. I've also filled a knee-hi nylon w/ash to use as a powder puff--again dusty for you & chicken. My sister does hers in a garbage bag w/only the bird's head sticking out then using the garbage back to scoop up the ash. You stay fairly clean. She said it would have been easier w/2 people since the bird kept trying to pull her head back into the bag so Sis was working one handed. I watch a guy on YouTube use a canvas bag and do a shake-n-bake method. Others hang the bird by the feet which, after they stop flapping, automatically causes the wings to fall open then you could use the powder puff or an old powder container or spice bottle with a shaker top w/big holes. Garden stores also sell a garden dust applicator like this one below--The Pest Pistol Mini Duster--$10. I like to use what I've got on hand. 
