On a Windows Box, installing PySide is as simple as
$ pip install PySide
followed by a quick download, and voilà. This is due to precompiled binaries being available for Windows. I often do this in a fresh virtualenv to test something. I recently had to find out that on Linux, no binaries are provided intentionally, and indeed I was not able to find any. Which turned a supposed 30 second installation into a 1.5 hour build affair.
Quite annoying, I must say! I would not want to do that every time I want a fresh install, so in my own interest the following link lets you download the wheel for PySide 1.2.4 for Python 2.7x built on a Linux Mint 17.3 Cinnamon x64 Bit.
The downloaded file can be installed with pip. Hopefully it is useful for someone else, too.