No official "werewolf cheat" exists in The Sims 2. Werewolves were added in the Pets expansion via gameplay: befriend the pack leader at night, get bitten. Any "cheat" is a custom mod (e.g., SimPE editing, InSIMenator, TestingCheats shift-click → "Give Werewolf").
Risks of mods: Save corruption, conflicts, instability. Always backup your Neighborhood folder before installing.
For legitimate lycanthropy: Buy Pets, find the pack leader at night, build relationship, get bitten.