Maybe it's possible to do it this way, but there's really not very much reliable information on the internet on this yet. Heck, I've heard rumors of wild werewolves in the game, but no one seems to be able to confirm this. The player's guide might have information on werewolves that's better than that found on the internet, but I've been hearing that there's stuff in the game that isn't mentioned in the player's guide. I've mostly just been assuming that the Companions Guild is the only way to become a werewolf because I have the Cursed Ring of Hircine, which is supposed to randomly transform you into a werewolf, of which the transformation part never happens. Of course there could be other reasons why the transformations do not occur, such as it being a glitch, but I don't know for a fact, and I'm not certain anyone currently does.
I have seen it stated that progressing through the Companions Guild is ONE way to become a werewolf, which seems to indicate that there may be more than one way to become a werewolf. I think only time will tell, when people finally figure out everything that is in the game, which likely won't occur until the Creation Kit is out and people can look at everything that's in the game.
Edit: From what I've been reading, I may have been right the first time about the Cursed Ring of Hircine not triggering any random transformations being a glitch, unless if Argonians are immune to the curse in this one. If anyone knows anything about this, let me know.
Edit: Actually, I might be right about the Companions Guild questline being the only way to become a werewolf in Skyrim. But I'm still confused.
@Other ways of becoming a werewolf - You're SUPPOSED to be able to contract the Lupinus disease (akin to how you become a vampire), which leads to...
@"wild" werewolves - The only other werewolves I've seen in the game so far (haven't been playing that long though) were those of the Circle, Sinding (Ill Met By Moonlight), and ONE in a cage in a Silver Hand dungeon (can't remember which one
). SO, in theory, getting attacked by one should give you the disease which will allow you to become a werewolf.
@Cursed Ring of Hircine - It DOES randomly transform you, at least it did for me (luckily I was in the wilderness
). Note, however, that I had already done the quest in the Companions Guild to become a werewolf; so it could be a glitch if you aren't already a werewolf.
@Ring of Hircine - Once you get the "uncursed" version, it will allow you to transform as many times as you want; when your transformation ends, put the ring back on and do it again. Of course, I was already a werewolf when I got this ring.
Once I get some more free time, I'll see if I can contract the werewolf disease on a character who doesn't already have it (provided I can remember which Silver Hand dungeon had the werewolf in the cage
).