Congratulations on your decision! I guarauntee you, that you will not regret it, and if you do, its not the end of the world (for me anyhow.) Below you will find the necessary steps to becoming a werewolf.
1. First, I recommend that you build you skills and level. If you go out trying to become a werewolf at level 1, you will most probably die. I recommend at least level 6. Also, its probably a good idea that your character have higher endurance and strength.
2. Find a werewolf. This is often the most difficult step. In lower levels, you will tend not to find many werewolves. You will, however, find a generous helping of wereboars, but who wants to be a giant walking pig? Once again, I recommend waiting until a higher level is reached. Look around in dungeons, and listen carefully for a howling noise. Follow it. You should find a wolf. Otherwise, you can sometimes find them while camping out at night in the wilderness.
3. Engage in combat with the loupe. Allow approximately 166 hits. This is because for every strike the werewolf makes he has only a .6% chance of infecting you.
4. Allow 3 days to pass. During the three days you should see a video clip of a naked man awaking from dream about the moon. Congratulations, you are now a wolf!
5. It is also a good idea to have the latest patch, as the early release contained a bug that turned you into a wereboar not a werewolf (ugh!)
AMENDMENTS BY PRIONACE
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* Having a "regeneration" type spell helps muchly when trying to get infected. Get hit a few times, retreat, regen a bit, then come back for more punishment. Hey, it's worth it, right?
* Huh. I always thought it was more of a snarling, growling noise that werewolves make, rather than howling... eh, nitpicking.
* If you can't take 166 hits and live (and many characters can't, unfortunately), just finish the fight (one way or another) and find another werewolf. Don't worry, it'll happen: some dungeons are positively CRAWLING with loupes (natural cave system-type places, for example: in those places, it can be hard NOT to get infected).
* There is no "instant notification" when you are infected, unfortunately. However, the VERY FIRST time you rest - or even "loiter" - after being infected, you will dream the "werewolf dream". In fact, you can sort of "cheat" with this: even if you loiter for "zero hours", you'll still get the dream, and you'll know of your fate right away! (Maybe you close your eyes for a few seconds, fall asleep, and wake right back up... who knows?)
* The special advantages and disadvantages "Immune to disease", "Resistant to disease", "Critical weakness: Disease", and "Low Tolerance: Disease" have absolutely no impact on lycanthropy or the chances of being infected with lycanthropy.
* However, "cure disease" spells will eliminate lycanthropy if they are cast before the 3 days are up.