The Mast Stepper is a must have item.
It's sold by www.catalinadirect.com. It's a bit pricy but solves several problems.
The Mast Stepper is a square metal rod that slips into the gudgeons where your rudder normally goes. It has a fork with a roller at the top and extends upward to cradle the mast just before stepping up or down. It also acts as a storage crutch in the off-season.
I've taken the diagram directly off www.catalinadirect.com.