On Ubuntu or other Debian based distro, setup your apt sources. See https://developer.sierrawireless.com/developerstudio for details.
Install Developer Studio for Legato by running:
sudo apt-get install devstudio-legato
To get the latest Legato version, go to the Package Manager perspective, and install it from the official Sierra Wireless repository.
You have the choice between two Legato versions:
Follow the provided interactive cheat sheet to run your first Legato Hello World application on your device.
Copyright (C) Sierra Wireless, Inc. 2014. Use of this work is subject to license.