Luke,
The partial girdling as Bob C. describes it was mentioned and pictured in an earlier post. It stops the flow of growth inhibiting hormones (auxins) to the dormant buds (these hormones flow downwards inhibiting bud growth).
Removing the top 6 inches of the apically dominant branch or trunk will allow bud formation along the entire main trunk, by removing the auxin being produced from the dominant bud. You then rub out the buds that you don't want to grow into laterals. You can then train any bud as dominant.
By only rubbing out the apical bud, you are not removing auxin production in the apex. This causes formation of numerous apical buds to replace the missing one.