You can add them to bump/displacement map as well. Chest or arms hair are usually flat. Pubic or armpit hairs could be more realistic if they are created as 3d prop.

I was busy last time and did not finished it, but I tried to make transmaped armpit hairs as dynamic prop. It was made with few one sides planes (quite low res 8x8 12x12) little bit folded each plane had separate transmap. I've seen something similar on toon figure. I'm not sure but I think that it was Gosha.