Get the PSR-0 autoload definitions by a post-update/post-install Composer script.

RefreshClasspath.php

<?php

namespace Dflydev\ClasspathResourceLocator\Composer\Scripts;

use Composer\Script\Event;
use Composer\Autoload\AutoloadGenerator;
use Composer\Repository\CompositeRepository;

class RefreshClasspath
{
    public static function refreshClasspath(Event $event)
    {
        $composer = $event->getComposer();
        $config = $composer->getConfig();
        $localRepos = new CompositeRepository($composer->getRepositoryManager()->getLocalRepositories());
        $package = $composer->getPackage();
        $installationManager = $composer->getInstallationManager();

        $autoloadGenerator = new AutoloadGenerator;

        $packageMap = $autoloadGenerator->buildPackageMap($installationManager, $package, $localRepos->getPackages());
        $autoloads = $autoloadGenerator->parseAutoloads($packageMap);

        //
        // Do something here to cache $autoloads somewhere that
        // my classes can find it and will always be available.
        //
    }
}