I assume that you mean that no BCC filters appear in the filters list in FCP? If so I would first check to see where the filters are installed. They should be installed in library/ application support/ final cut pro system support /plugins /Boris Continuum Complete x.x (where x is the version number). This is the library folder in your root directory, not the user folder. If it's not do a search for the word Continuum to see where they are. You can simply move them to the correct folder. The Boris installer should put them in the proper directory, but it's worth a look.
I'm having the same issue. I've installed a few times now and though I can see the effects in the proper folder they aren't showing up as effects options in the Final Cut Pro 5.1 menu.
I have an upgraded project that is riddled with Boris CC effects and they can't find themselves.
I'm also on a new machine - having gone from a G5 dual 2G to an Intel MacBook Pro. Now I'm wondering if BCC isn't compatible with Intel chips. But shouldn't that make it work slowly rather than not at all?