Are you talking about hackle quill bodies like A.K. Best uses, or peacock quill?
At any rate, if hackle quill bodies the easiest method is simply strip the fibers from the quill and tie it in by the tip (I know you can't strip the hackle all the way to the tip, just tie it in by the very end of the stripped portion.) Tying the quill in by the thin end like this produces a nicely taped body and is the way Art Flick used to tie his quill bodied flies. If you happen to have brittle hackle quills, simply soak them in some water that has some hair conditioner added to it for an hour or so. The hair conditioner will take the brittleness away because it contains glycerol and after the quills dry, they won't split.
If peacock quill, put about a tablespoon of bleach in a glass or stainless pan or container and a cup or two of water. Add the peacock eyed section to the bleach and water mixture, swish the peacock around until you start to see some flecks show up in the bleach and water mixture (this indicates the flue is being burned off the peacock). Then take the peacock out of the bleach solution and dunk it into a container of white vinegar to neutralize the bleach for 30 seconds or so, and then rinse under luke warm water. After this, I put the now stripped eyed peacock in hair conditioner and water for about an hour. Once the peacock is dried, you will find the flue has been removed and you will have nice flexible stripped peacock to tie with. Stripped peacock should also be tied in by the tip.
The flue on eyed peacock can also be removed by rubbing an individual fiber with an eraser (takes too much time for my tastes). The eyed tail can be soaked in common parafin wax, allowed to dry, and then the flue is simply stripped off by running the fiber between your fingernail and thumb pad.