PyBitmessage can be run in deamon mode by adding this line to your keys.dat file under [bitmessagesettings]:
daemon = true
In this mode, PyBitmessage doesn't require Qt. You will then need the API. If you do not yet have a keys.dat file because you have not yet run Bitmessage, run it. It will create the keys.dat file for you then exit if it cannot find PyQt.