First I created 3 types of hair cards each for differing lengths of hair. The hair cards were curved to match the roundness of the head and the central edge was raised slightly to presumably create a better shading result later on. The UV islands were 1/8 the width the UV space.
I then selected an area of the head where hair would go, duplicated the faces and made it into a separate object.
I created additional bending/curved hair cards from the first longest hair card. They all kept the same rectangular UV layout though.