Well, at OA LIVE was so very intelligent to install the content into a folder only available in-game when in Multiplayer/online play.
Locate that folder and copy it into the FO3 directory, there should be an .esm file for BS to activate as well. Just do a Search for ".esm", including hidden folders, and there it should be.
Maybe that solves the problem with BS as well?
Besides, LIVE is true and utter - sorry - cr**. Even when I wanted to give them money (=buy their obscure "ms-points") they didn't let me - "come back later". Big deal. Any other shop would have to close in a minute with such support, but certainly not m$. I can't imagine why Bethesda associated with them exclusively for the downloadable content (on the other hand, it fits: DLC with their download/install routines go the classic way, We Know Better Than You, We Install For You, You Don't Need To Know, Anyway You Are Stupid)).
So I am still awaiting BS ... Correction: I got it, finally. By opening a new account and paying via that new account. Oh by, I don't like them ...