This is what I believe he was talking about, I do this every year to mine. Bill V. wrote this description of the technique in my beech thread:
A tip, remove each terminal bud now, before they open, as they swell. Then carefully open the other buds, in a few days, and remove the center growth. This will stop elongation, develop small foliage AND you will not need to trim your Beech for the rest of this season. This technique is used for developed bonsai like yours, not trees which still need development.
Please note that you will need to do this several times a day, because they open at different rates, and it may take several days or a week to complete.
http://www.bonsainut.com/threads/beech-wired-and-ready.7047/page-4