How to use TeX Gyre fonts installed by TeX Live
In my installation (MacTeX 2012) the fonts seem to be located into /usr/local/texlive/2012/texmf-dist/fonts/, especially into the "opentype" and "truetype" folders.
If you can't find them, you can try running:

locate tex-gyre


Once you have located the fonts, to install them just copy them into ~/Library/Fonts (user-specific) or /Library/Fonts (system-wide).