The best way to install PyQt is to install Anaconda which contains PyQt4 in its site packages folder. Make sure to install from this link as the newer Anaconda installations have python 3 and PyQt5 which will not work as well on the embedded side of things. Once you have pulled down Anaconda from the link above click on the file to install it.
You can select whatever option you like but I typically install everything for all users.
The default is C:\ however I have more space on D:\ so that is where I installed my Anaconda.
You want to make sure that the system recognizes the Anaconda python as the main python for the system in order to run code from the command prompt.
When the installation is finished you can navigate to the command prompt and type python to verify that indeed the Anaconda python is that version that comes up. Congratulations, you are ready to use PyQt!