Taking a peice of straight antron. Seprate out a section half the thickness that you want the post and at least 2 and a half times the length. You can sub in marcoma yarn {cheaper}for the antron, both float equally well.
Hang the atron from the vise with a set of hackle pliers on the other end of the peice of antron and a dubbing spinner hanging from the hackle pliers. Spin the antron around using the dubbing spinner until the antron wants to fold upon itself. Fold the spun antron in half back onto itself so that it spins itself together like a peice of shag rug.
Remove the atron from the vice and its ready to be tied onto the hook. It will not unfurl itself and will hold this shape well until you cut off the loop on the one end. Then it will unfurl itself and fluff up to a nice looking wing. This should be done as the last step in tying the fly.
When doing extended bodies using furling you do not remove the loop.

The main place I myself have seen Furling used in fly tying is to do extended bodies on adult Hex, crane fly and dragon fly paterns. Though recently at a fly fishing show I saw a guy use it to do a body for a sac fry. Other then myself I have never seen anyone use it for parachute post.

For a cheap dubbing spinner glue a cup hook into any old brass cabinet knob.