Really, the lore that everyone knows about werewolves is pretty recent anyway. If Wikipedia is to be believed, the idea that werewolves are only harmed by silver weapons only dates back to the nineteenth century. Older weaknesses for lycanthropes include rye, mistletoe, mountain ash, and wolfsbane (the latter of which actually was used in the Canadian Ginger Snaps movie series, which I believe also dismissed the silver thing). Also, while modern werewolf stories often focus on people being changed against their will, old European tales tended to be about witches and wizards who voluntarily turned themselves into wolves to carry out the Devil's work. The idea of lycanthropy being contagious also seems to be a more modern development, possibly borrowed from vampire lore.
One classical myth that a few websites mention as a possible source for the werewolf concept is the Greek tale of Lycaon of Arcadia, who presented human flesh to Zeus. Sound familiar? Instead of being tantalized in Tartarus, however, Lycaon was transformed into a wolf. Some versions of the myth say that his children also became wolves, while others simply say that Zeus killed all or most of them with thunderbolts.