The description states that he used a custom texture pack, nothing more. In this pack he made a bunch of iron blocks with text on them. He also made Wooden pressure plates invisible, and had placed them over the 'buttons'. Pretty ingenious.
"'Tis true, 'tis pity, and pity 'tis 'tis true." -- Poloniouius, in Willie the Shake's _Hamlet, Prince of Darkness_