Contact your local Scripps-Howard newspaper (scripps.com) or the sponsor of your local spelling bee. Inquire about a local Home Schooling Association that is holding a spelling bee. If there are none in your area, your child may be able to enroll in the spelling bee held at the nearest public school.
Inquire at the Home School Association or public school for enrollment into the bee. Fill out the necessary paperwork for enrollment.
Obtain a copy of "Paideia"--a booklet of words that will be asked in the spelling bee--from the Scripps-Howard newspaper sponsoring your local bee. Encourage your home-schooled student to study it for a few hours a day and quiz him on the words. Start with the words in the "Beginners" section and gradually work up to the words in the "Advanced" section of the booklet.