Waxing up teeth involves wax, a colored marking pencil, a tooth peg, dentoform/typodont, bunsen burner, specialized instruments, knowledge of dental anatomy, a good eye for detail and nylon :) for the sparkle. The actual waxing skills are developed on the way.
Waxing up is in essence building a tooth from wax. Now this may sound easy but keep in mind that this has to look like an actual tooth and actually be functional, i.e the aim is to reproducibly relate the maxillary (upper) and mandubular (lower) teeth; they must contact each other (not too long, short, thick or thin). This ordeal includes placing and removing wax, making marginal ridges, sealing margins, shaping the tooth, establishing occlusal contacts, and evaluating the final wax-up.
**On another note, it's Mental Monday! Go here for today's trivia and to see last week's answer and winner**