The answer I eventually came up with was using the code below.
from PyQt4 import QtCore, QtGui
from locale import getdefaultlocale
app = QtGui.QApplication(sys.argv)
locale = getdefaultlocale()
translator = QtCore.QTranslator(app)
translator.load('/usr/share/my_app/tr/qt_%s.qm' % locale[0])
app.installTranslator(translator)