A spinner is someone who spins. Say, for example, me. I'd be happy to help you out if I lived in the same time zone.
Wool roving is what spinners use to make yarn; it looks more or less like this:
You can buy it online, but since you don't care about color, you might have some luck with contacting Lynn's Texas Fiber and asking if she has any cheap fiber or dye experiments gone bad that she can sell you. Explain what you want to make, and she might be able to hook you up.
As for how to go about making them, there are instructions here: http://www.woolcrafting.com/wool-felt-insoles.html What they don't tell you is that you don't have to wear socks in the shoes after you've put in the insoles. I mean, you can if you want, but you won't need to. Eventually they will conform to your foot and be incredibly comfortable.