As a benefit for the Great Peace March, Carlton Hair International in Westside Pavilion will sponsor a "cut-a-thon" from 11 a.m. to 6 p.m. Saturday. Fourteen stylists, working three-hour shifts, will cut hair for a $10 minimum. No appointment is necessary. Proceeds to go to the march. About 300 marchers who left from California are expected in Denver on Sunday, one third of their way to Washington in their appeal for global nuclear disarmament.