brew install pyside --with-python3
brew install pyqt --with-python3
brew linkapps

Hopefully this should install PySide for both Python 3 and 2.7. PyQt will also be installed for 3 and 2.7.

The dependencies will also be installed, i.e. SIP, Shiboken, Qt etc.

brew linkapps will just symbolically link the apps installed with Qt (the designer etc. that will come in handy later), to your Applications folder, which is practical for access.