Dehairing shorn llama fiber is a bit different from dehairing cashmere, in my experience. The hair in both is quite thick, shiny, and stiff, but in cashmere it's alot different from the down, where in the haired llama I've seen, it's not as different from the underlying coat.
With either llama or cashmere, I recommend washing the fiber (and hair) first, as you can raise quite a dust-storm dehairing it while raw.
If you hold a pinch-full of washed llama fiber up in very good light, you should be able to pick the hairs out by hand, same as with cashmere. Bend it over your finger to help accentuate the stiffer hairs from the fiber -- they won't be as bendy and will even sometimes pop up ends conveniently for you.
I remember several years ago seeing a contraption of two stiff-wire-mesh squares for dehairing llama. You'd lay one on a table, put a thin layer of llama fiber on top of it, put the second on top of that, pin them together, then hold it up to a light and pick out the hairs (with tweezers? or maybe spring-loaded pliers?)
It all makes me very happy to have fiber llamas, without the second hair coat except in their britch and on their chests!
(based on a post by me on spindlers 19 April 2007)