For the most part, standard QtSixa setup that [you'd find online][setup] and a [more complete one here][setup2]; built it from source. I did use Retropie's Sixad fork, though because it seems to have additional updates, specifically regarding the driver start functions in the /etc/init.d/sixad
file.
That means, stop when you see these steps
wget http://sourceforge.net/projects/qtsixa/files/QtSixA%201.5.1/QtSixA-1.5.1-src.tar.gz
tar xfvz QtSixA-1.5.1-src.tar.gz
You should instead do