Well, if you've done it right, you should have a line like this in your Oblivion.ini file:
SArchiveList=ArchiveInvalidationInvalidated!.bsa, Oblivion - Meshes.bsa, Oblivion - Textures - Compressed.bsa, Oblivion - Sounds.bsa, Oblivion - Voices1.bsa, Oblivion - Voices2.bsa, Oblivion - Misc.bsa
[/xml]
There should also be an ArchiveInvalidationInvalidated!.bsa file in your Data directory. If you used the OBMM method, the path will be slightly different, but once again you should find a dummy BSA file in the directory listed in the SArchiveList. The SArchiveList is relative to your Data directory.
Btw, I'm not sure about the OBMM instructions posted above. I think that's the old method.
I just click on Utilities, Archive Invalidation, make sure BSA redirection is checked off and click Update Now. That's it. Done.
You'll wind up with a file called BSARedirection.bsa in your obmm folder in your Oblivion directory (not data) and your Oblivion.ini file will have:
[xml]
sArchiveList=..\obmm\BSARedirection.bsa, Oblivion - Meshes.bsa, ... other bsa's