Brian, thank you for trying to help. Unfortunately, on the Mac the alias solution (suggested by Steinberg) doesn’t seem to work. The error message says nothing useful, and there is no log one could analyze to try to find a solution.
As for the symbolic link, the Terminal says that permission to complete the ln -s operation is denied. I can’t understand why, but it is probably because the Library directory is a reserved (and protected) one.
This type of things is usually easy on the Mac, but this doesn’t seem to be the case.