You can try this ps3controller module:
https://github.com/gizmo98/RetroPie-Setup/blob/ps3-gasia-hack/scriptmodules/supplementary/ps3controller.sh

Or type…

mkdir test
cd test
git clone --depth=1 https://github.com/gizmo98/RetroPie-Setup.git
cd RetroPie-Setup
sudo ./retropie_setup.sh

…and (re)install ps3controller