You can use the powder form of permethrin or the spray on the birds.  Make sure if it's a concentrate liquid you dilute it according to the package directions for using on poultry.  Spray works best for the coop, to get into all the nooks and crannies.  Remove and discard all bedding and nesting material before spraying the coop, and replace with fresh once it's dry.  If you use a permethrin powder many find it easiest to use a condiment squirt bottle, to get it down to the skin.  Either way, separate feathers, and get the product done to the skin where the bugs are.  If it's cold where you are then powder is preferred so as to not chill the bird.  If it's warm, spray is probably easier.  There are good instructions and information in the link I gave you in my first post here.  The biggest difference between the permethrin and the Elector PSP, other than price, is that the elector is supposed to be effective with just one treatment.  With the permethrin you should repeat weekly until you don't see any more.  I would also, using nitrile gloves, try to manually remove some of those nits, pull/scrape them off and dunk them in soapy water.  The more you get off the faster it will go.