composer.php

$autoload_functions = spl_autoload_functions();
$loader = $autoload_functions[1][0];
$embeddedComposerBuilder = new Dflydev\EmbeddedComposer\Core\EmbeddedComposerBuilder($loader, '.');
$embeddedComposer = $embeddedComposerBuilder->setComposerFilename('test.json')->setVendorDirectory('testDUMP')->build();
$embeddedComposer->processAdditionalAutoloads();
$io = new Composer\IO\BufferIO();
$installer = $embeddedComposer->createInstaller($io);
$installer->run();
$io->getOutput();

test.json

{
	"name": "laravel/laravel",
	"description": "TEST",
	"keywords": ["framework", "laravel"],
	"require": {
		"dflydev/embedded-composer": "dev-master"
	},
	"require-dev": {
        "phpspec/phpspec": "2.0.*"
    },
	"autoload": {
		"classmap": [
			"app/commands",
			"app/controllers",
			"app/models",
			"app/repositories",
			"app/services",
			"app/database/migrations",
			"app/database/seeds",
			"app/tests/TestCase.php",
			"app/specs/SpecObjectBehavior.php"
		],
		"psr-0": {
        	"Foundry": "app/lib"
    	}
	},
	"scripts": {
	},
	"config": {
		"preferred-install": "dist"
	},
	"minimum-stability": "dev"
}