Instructions
Create a PC with the Longtooth version of the Shifter race in the PHB 2. Select the Druid class and multiclass into the Barbarian at second level. This will give you the ability to transform into a wolf form (Druid power Wild Shape). Several of the other Druid class powers work very well with a werewolf build, including Grasping Claws, Pounce, Savage Rend and Darting Bite. Barbarian powers that work include Howling Strike, Bloodletting, Bloodhunt Rage and Primal Vitality.
Create a Razorclaw Shifter and multiclass Druid and Monk. This gives you unarmed combat as well as wolf form. You can rename the monk feats to give them werewolf flavor without changing the underlying mechanics (power type, to hit, damage).
Use a player-created werewolf template. You can find these on the Wizards of the Coast Community Forums and elsewhere. Check with your dungeon master to make sure that the build is not overpowered.
Make your own werewolf PC race. Give a plus two in two stats, a bonus to two skills and a few race-specific bonuses or powers. When selecting these bonuses, pick abilities that work thematically and that aren't too overpowered. Using the racial bonuses for Shifters is a good way to ensure you don't create a race that's too powerful. Select a class as usual.
Make your own werewolf PC class. Select a playable race as usual. Select a role for your werewolf class. Striker is probably the best choice. Select a power source. Primal is the most logical. Determine which two or three abilities are primary ones. Strength, Dexterity, Wisdom and Constitution are all possible choices. Determine armor and weapon proficiencies. Select which defenses will get a bonus. You get a total of two bonus points, which you can assign to one defense or split between two. Select starting hit points and points gained per level. Fighter classes start with 15 and get six additional hit points per level. Select three trained skills. Select a base class feature. This will be a power of some sort, most likely an encounter power. It is best to choose an existing power from another class. Select At-Will, Encounter and Daily powers for first level. Look at the druid, monk and barbarian classes for good powers that can easily be reskinned.