There will no doubt be a bunch of XML errors due to accented characters - the Mac version can't handle them. They can be eliminated by "zapping gremlins" using BBEdit, or some equivalent program.
The mod may also use Dr Elmer Jiggle's CvPath.py module, or a derivative of it, which provides the folder paths on the system for the rest of the mod. Unfortunately CvPath.py assumes it's running in Windows, and so fails to get the data it needs on a Mac as there's no Registry. That's fixable by using the cross-platform version of CvPath.py that I posted elsewhere. Other file paths in the mod may also be calculated wrongly if the modder assumed it was running on Windows (back slashes instead of forward ones).
The third one, and this could be a show-stopper, is that I believe FfH uses a custom DLL created using the Windows SDK. That simply will not run on the Mac version of Civ4 until (a) we get a Civ4 SDK (software development kit) for OS X and (b) the FfH dll source code is then ported to OS X.