UPDATE: 2016-01-05 Advanced Launcher has been discontinued by its author and all links to its repository have been deleted. I am investigating alternatives and will post again once I have an answer. Until then, please check the comments section for further information.
Advanced Launcher is an add-on for Kodi that is used to launch external applications such as Firefox or Steam in any operating system. Launcher parameters are customisable so a particular instance can launch a specific website, game, or media file. In short, if it can be defined in a command-line interface, it can be done through Advanced Launcher.
Unfortunately, such awesome power is not available to Kodi users by default. To install Advanced Launcher, you will have to add the Angelscry repository to Kodi’s source list. To access the source list, navigate to the “Files Manager” under the “System” menu.
Choose “Add Source” and type
http://www.gwenael.org/Repository as the path. Name the source “Angelscry Repository” and click “OK”.
From the Settings>Add-ons Menu, choose “Install from zip file”. When the browser appears, select “Angelscry Repository” from the list and wait for it to connect to the server.
Select “repository.angelscry.xbmc-plugins” from the list and choose the latest version of the repository to install. Back out to the Add-ons menu and now choose “Get Add-ons”. Select the newly-available Angelscry Repository, then “Program Add-ons”, and finally “Advanced Launcher”. The add-on will now be available from the “Programs” menu on the home screen.
Creating a standalone launcher (for a single executable like Firefox) is a simple process of browsing to the executable for the application (or just entering the command in Linux), defining the command-line parameters, and providing a (optional) thumbnail. The add-on walks you through the process and you will be able to set these launchers as favourites or (in the case of the Aeon MQ5 skin) home menu items.