Youd have to get some spacers/adapters for them, which would run 300-400 from what ive been told by people when i asked for them. I really wouldnt recommend it as its not cost effective, and for a lesser price you could get a same style of wheel in your lug pattern that looks the same.
If you are interested in a similar wheel to the tC that will fit the xB, check out the Enkei EVO6. They are a split 6 spoke and come in two finishes, hyper black, which is what I have, and anthracite, which is darker, almost like a black powdercoat. Here's a pic of mine on Enkei EVO 6 18s.