Here are a couple videos about lowering masts on small sailboats for the DIY folks.

First, a keel-stepped mast using a gin pole. Courtesy of the Port Townsend Sailing Association.

Video: Steve Scharf

Second, a deck-stepped mast using the boom. There was also a write-up on this in ‘Lectronic Latitude – Lowering the Mast on a Small Boat with The Resourceful Sailor.