There's no way to do that in FTP. I'd have to do it with something like SSH, which means (1) knowing the OS the ftp server is running, (2) logging in as root (or at least some kind of admin user), (3) navigating to the appropriate directory, and (4) running the appropriate chmod/attrib/acl/whatever command.
That's not likely to happen. But feel free to implement it as a plugin!