First of all download the original mod - here: --> http://www.nexusmods.com/skyrim/mods/48470/?

That offers an interface for... well, they're wigs, technically. But it's almost as good as being able to change NPC hairstyles at a whim.

Now download the fixed ESP --> LycHairstyler.esp

in which I basically just ran through every single wig in the creation kit and added the SexLabNoStrip keyword to all of them.

Have fun.