pifacecad-emulator is in the Raspbian repositories. Install with:
$ sudo apt-get update && sudo apt-get install python3-pifacecad-emulator
Uses Python 3 because of Barrier in threading.
Run the build_ui.sh script to build the UI first (you only have to do this whenever you make a change to the UI in designer-qt4)
$ ./bin/build_ui.sh
Test with:
$ python3 tests.py
Otherwise, use just like you would pifacecad:
$ python3
>>> import pifacecad_emulator
>>> cad = pifacecad_emulator.PiFaceCAD()
>>> cad.lcd.write("hello")