I use Macports for GnuRadio dependencies on OS X. For itpp see
https://www.macports.org/ports.php?by=name&substr=itpp
Install Macports (if you want to use it). then 'sudo port install itpp’, Macports will
install itpp’s dependancy for fftw-3. You can also 'sudo port install gnuradio’. But
before anyone installs via Macports make sure to uninstall same packages installed from/by
other means to avoid conflicts.
Dom