The first thing you will need is the qt4reactor, which you can find on twisted's trac server.
<notes: next step, do you need to install it before you can call it? How you do that, I'm not sure.>
<note: Ed Suominen has written a module that allows you to "construct a non-blocking modal dialog, immediately obtaining a deferred to the user's eventual input". I have absolutely no idea how to call this module.>
<note: This has no content! Here's some working code for integrating PyQt4 with Twisted: http://eli.thegreenplace.net/2011/05/26/code-sample-socket-client-based-on-twisted-with-pyqt/>