Earn the "Buddies with Toorum" achievement, then start a new game. During character creation, name the hero in the first slot "Toorum" (without quotes), then confirm. A sound effect should play, and your lead character essentially becomes a playable Toorum, complete with his unique stats.

Note: If you choose to create a Toorum character in this way, you cannot have any other adventurers in your party. On the other hand, Toorum can become strong enough to be the equal of a full party.