I wonder if you can drill a small hole at the fixed cup flange (if it has enough material sticking out past the BB shell) and safety wire the thing to the chain stay near it so it does not loosen up.......
I just hate the idea of tightening the thing like crazy or using thread locking compound on it...then end up having a big problem later trying to remove it from the frame if you have to replace it.....

Chombi