Now I can use my awesome controller on my PC.
Apparently the mouse and keyboard libraries for the Galileo board have not yet been implemented (or at least I coudn't get them to compile).
So, because I didn't want to write my own libraries I used Qt Creator and an existing example to read serial data from the Galileo board and the Qt application translates that data to mouse/keyboard commands:
I played a few PC games with the controller and it works flawlessly. Only problem is that the controller is not that easy to handle but it works fine for simple games like Pacman or Solitaire.