Metolius offer bolt-on climbing holds, which attach to your climbing wall with a 3/8 inch bolt that screws into a T-nut and is the most common method for mounting climbing holds. They also offer screw-on holds. These holds are designed for plywood walls and attach using several wood screws. There are many options for ordering different quanities of holds by specific set or a mix so you can get exactly what you need.
Read more at http://www.ukclimbing.com/gear/news.php?id=3573