"But the vast majority of wolf owners find their wolves are untrainable, unpredictable as adults - and even menacing, especially near small animals and children."
http://www.wolftrust.org.uk/petwolves.html
You can't "train" wild animals. Either they have been domesticated over many generations or they have not. A wolf is a wild animal that could never be trusted. There are however wolf hybrids, but even then I've heard that only really experienced people should keep those as they retain quite a bit of behavior from the wolf side.
A full blown wolf? I'd avoid that unless you are the type to also keep a Lion.