Henrik Bjørnskov has a quick new post today showing how to combine two powerful technologies into a simple, configurable autoload system in a Symfony Travis-CI build with Composer.
To integrate your project with travis the only thing necesarry is to have a .travis.yml file and a working PHPUnit test setup like http://github.com/simplethings/SimpleThingsFormExtraBundle. Where the Tests/vendors.php script is executed before the tests are perfomed. But it would be way cooler to just have Composer handle the autoloading and dependencies.
A sample .travis.yml file is included in the post (also here) as well as instructions for grabbing dependencies and including the autoload process in your application's bootstrap.