Hmm... I had never heard of a tambour needle. Looks like it may be promising. It would be the opposite approach in that you would be pulling the feather from the outside to the inside.  Maybe you could somehow "fasten" the end of the feather between the fleece and foam. Thinking maybe you could leave the back seam of the fleece open so you could get in and pull through feathers then glue down to the foam as you work your way back.

I am off to explore the word of tambor to see what other stitches there may be. If there is one that could leave a long loop on the right side of the fabric you could do do hair that way in either yarn or embroidery thread... hmmm.

Yeah, it's pretty obscure. Comes from a small French town (I forget the history) but supposedly got there from India... I think. I got into it after watching the French film "A Common Thread" which showcases the fantastic needlework and process of making it:
http://www.imdb.com/title/tt0387892/

The idea as far as I can gather is that it's much like crochet, only on fabric. The needle plunges down through the underside of the fabric, you do a funny twist with your wrist and at the same time pull the needle back up (the eye of the needle goes through the fabric but not the whole needle itself), which creates the first stitch. You twist your wrist again, plunge down a tiny bit further in the direction you want to sew in, and repeat the steps; this creates a chain stitch. Your other hand is holding onto the thread on the other side (right side of fabric, facing away from you) which is important because this tension is what keeps the chain stitch from falling apart and what aids in keeping the thread attached to the needle on the other side. As I said, I've not mastered this myself so I'm not sure how easy it is to do with feathers. And actually, I should have mentioned: it's a MUST to do this technique before attaching the fabric to anything. You have to have easy access to both sides of the fabric in order to be able to reach under the fabric to hold the thread; see above about tension.

You can do this stitching with plain thread, but the movie shows how you can add sequins, and I know from reading that you can use buttons, beads and other things. So theoretically if you had a long quill you might be able to thread it in with the chain. The way you 'finish' the tambour stitches is simply by taking the end of the thread and weaving it back into the chain of stitches; no knotting off required. You could weave the quill into the stitches in the same way, although I suppose that depends on how tough/strong/flexible the quills are.

The way the stitches work when you pull the needle back up towards you. This means that on the right-side of the fabric there will be a loop of thread, so it would be theoretically possible to start the stitch, have the loop on the right-side, hook a feather quill, pull the needle back up and thereby tighten the loop around the quill, then continue on.

If you have trouble understanding the process I believe there's a clip or two on Youtube of some of the above movie which shows the steps. There's probably a tutorial or two as well. -- Apparently tambour needles are pretty hard to find, and a scant few European stores stock them. However I was lucky enough to find one on Amazon.com for $30. Comes with a couple of needle sizes and the holder. I really wish I had more time to learn it, because it's really quite beautiful when done well.

It's probably more work than the other ideas, I'd just wondered if anyone had tried it.