The simplest way to raise and lower a sail is through a "dumb sheave" or a rounded hole in the top of the mast. A simple way to achieve this is by rocking a drill bit. The result is a kind of half sheave. Mike O'Brian boasted the effectiveness of this technique in a recent issue of his Boat Design Quarterly. (Available from Woodenboat Magazine www.woodenboatstore.com/ ) He's used it on sails up to 240 sq. ft. On small masts you can use a router quarter round bit as well. 

Using 3/4" stock and a 3/8" quater round router bit* you can make as many fair leads as you need. The hole size chosen depends on your line size and also the size of the tip or bearing on your router bit. 

(*Using any radius bit half the thickness of your stock will result in a semi-circular cross section when rounded.)