Steps for reproducing the HPCE-2015-GPU-Image AMI.
Start with the image debian-jessie-amd64-hvm-2014-12-25-13-19-ebs (ami-aae18fc2)
on a GPU instance.
Then do:
sudo sed -i -e "s/main$/main contrib non-free/g" /etc/apt/sources.list
sudo apt-get -y update
sudo apt-get -y install nvidia-libopencl1
sudo apt-get -y install nvidia-opencl-icd
sudo apt-get -y install nvidia-opencl-dev
sudo apt-get -y install nvidia-driver
sudo reboot
@schmethan suggests also installing eog and libcanberra-gtk3-module for viewing images.