How do i go about adding Chaco to an existing PyQt4 application?

Hours of searches yielded little (search for yourself). So far i've figured i need the following lines:

import os
os.environ['ETS_TOOLKIT']='qt4'

i could not find PyQt4-Chaco code anywhere on the internets

i would be very grateful to anyone filling in the blanks to show me the simplest line plot possible (with 2 points)

from PyQt4 import QtCore, QtGui
import sys
import os
os.environ['ETS_TOOLKIT']='qt4'

from enthought <blanks>
:
:

app = QtGui.QApplication(sys.argv)
main_window = QtGui.QMainWindow()
main_window.setCentralWidget(<blanks>)
main_window.show()
app.exec_()
print('bye')

what Chaco/Enthought class inherits from QWidget ?