I believe the topping lift is just to hold up the boom when there is no sail raised and is left totally free when sailing and not a sail adjustment.
I just looked through the owners manual someone posted under owner modifications for a 26c. It shows nothing as far as boom lifts go. Mine came with a 5/16 rope running from the masthead to the end of the boom. I just tie off the boom at level or just above with a bowline. However, this method makes small adjustments under sail difficult to do. May have to add a pulley and longer rope. However, for now what I have is satisfactory.