We'll assume that you've already installed ROS Hydro from those instructions using the recommended proposed solution.

The packages for the Shadow Hand are not released as debs for Groovy, so you will need to install them from source.

To get our software, run the following commands from a terminal:

$ sudo apt-get install ros-groovy-pr2-desktop ros-groovy-pr2-robot ros-groovy-arm-navigation  ros-groovy-pr2-simulator ros-groovy-diagnostics-monitors python-rosinstall python-rosdep git -y

$ mkdir -p ~/workspace
$ rosws init ~/workspace /opt/ros/groovy
$ source ~/workspace/setup.bash
$ cd ~/workspace

$ rosws set  shadow_robot --git https://github.com/shadow-robot/sr-ros-interface.git --v groovy-devel -y 
$ rosws set  shadow_robot_ethercat --git https://github.com/shadow-robot/sr-ros-interface-ethercat.git --v groovy-devel -y
$ rosws set  sr_visualization --git https://github.com/shadow-robot/sr-visualization.git --v groovy-devel -y
$ rosws set  sr_config --git https://github.com/shadow-robot/sr-config.git --v groovy-devel -y

$ rosws update

$ source ~/workspace/setup.bash
$ echo source ~/workspace/setup.bash >> ~/.bashrc

$ rosdep update -y

$ rosdep install shadow_robot -y
$ rosdep install shadow_robot_ethercat -y
$ rosdep install sr_visualization -y
$ rosdep install sr_config -y

$ rosmake shadow_robot
$ rosmake shadow_robot_ethercat
$ rosmake sr_visualization
$ rosmake sr_config

$ echo source `rosstack find sr_config`/bashrc/env_variables.bashrc >> ~/.bashrc

Bear in mind that if you are using a real Shadow robot etherCAT hand you will need to check out the specific branch of the sr_config repository that contains the parameters for your hand (instead of the groovy-devel branch in the commands above.