I don't know about pyqt, but wxpython will not work with ArcGis--just doing an 'import wx' in the python window, or in a tool script, will crash the entire application (event loop clash, I suspect). However, you can use wxpython outside the app framework and communicate with it using comtypes and the approt process. As mentioned above, Cederholm's instructions will get you started nicely.
Mike