http://fallout3nexus.com/downloads/file.php?id=640
top menu under tools BSA unpacker/Creator.
If you didn't use that to unpack then what did you use?
Also please let us know how the results turn out. I'm curious and have not heard of anyone doing F3 meshes or if all the same meshes are safe to do.
I've also not felt I needed it. I put in the heaviest replacers and the game still runs fine with 250 mods.