Yep, that is what I do. If you have a bad infestation I would clean the coop. Spread Sevin on the roosts, nests, and anywhere else the birds hang out. Put in new bedding over the dust. Then dust the birds well with the Sevin. Also, if they have dust baths or areas they bathe in the yard, etc., then I would spread Sevin there, too.
Moodychicken gave me the best advice when I first got on here. I thought I had a mite problem and she told me this:
Mix alcohol and Sevin (or permethrin) in a squirt bottle. I think it was like a gallon of alcohol to a tbsp of Sevin/Permethrin.
Spray the birds down. Spray the roosts and all areas of the coop when you clean it out. I'm a little paranoid because I hate creepy crawlers, so I spray the coop down with that alcohol mix every two weeks. I've had no problems since. It's a great preventative and the birds like the spray down every once in a while. Good Luck and keep us posted.