Get a pillow case and put a pile of sevin dust in it. Then put a chicken in the pillow case with its head sticking out the top of the pillow case. Grab the chicken by the neck snugly and gently 'shake and bake,' rolling the chicken around inside the pillow case. Then pull her out and rub some dust on her head and neck. Dont get any dust in her eyes or nostrils. Then let her go. She'll shake herself off and go about her business. Wear a mask and old chicken clothes and shoes.
To dust the coop: Put a pile of sevin dust at the entrance to the coop. Get your leaf blower and hit the pile full blast. I guarantee you that every nook and cranie inside the coop will be dusted. Let the dust settle before letting chickens go inside the coop. Wear a mask, old chicken clothes and shoes.