Andrew Embler has posted a guide to his site showing you how to use Composer with concrete5 to integrate third party libraries quickly and easily. concrete5 is an open source content management system under the MIT license and is flexible and easy to extend.
He uses this particular package as an example, showing you how to create the
composer.json file to include the LavaCharts library and run Composer to install it. He then shows the integration of the package with the concrete5 CMS instance, including the Composer autoloader in the "on start" handling. From there it's just a matter of referencing the library via its namespace and using it to populate and generate the resulting chart.