HOW TO NEEDLEFELT DOLL HAIR
You need a special needle for needlefelting. You just keep poking that needle in & out over your hair and the little prongs on the needle poke the hair into the dolls head. No need for glue or stitches.
It will work with any fiber that isn't real slick. Most yarns would be fine and of course the best is wool. It also depends upon what you are needlefelting into. If you've stuffed your doll with rags, it won't work. There isn't really anything in the rags that helps hold the fiber beneath the outer cloth. The needle kind of intermingles the fiber you are attaching with the fiber that is packed inside. And since rag stuffing is kind of hard, the tip of your needle will break off. If you've stuffed with wool or Polyfil, needlefelting will work great.
You can get the needles at sistersanddaughters for $5. When you get a needle, hold it up to the light and you can see the little barbs on it. If you have something very skinny that you are needle felting, you can get a thick piece of foam rubber or something similar and lay your item on it, then needlefelt and it will save your fingers.