Like what Mark said, but you could also have the hair object attach and show on the same domain, but change the properties of each hair -e.g. some long, some short, etc. The shading domain is assigned in the vertext room - select faces from the object and assign (rt tool set) a new shading domain, then if you like, assign a shader... this can be used instead or with UV mapping. Question of my own - would you assign domains for export into Poser when setting up zones for rotation/ body parts?

Never Give Up!