composer.json

{
  "name": "test-vendor/test-project",
  "type": "project"
}

packages.json

{
    "packages": {
        "test-vendor/test-project": {
            "dev-master": {
                "name": "test-vendor/test-project",
                "version": "dev-master",
                "version_normalized": "9999999-dev",
                "source": {
                    "type": "git",
                    "url": ".git",
                    "reference": "4ba8b76fb2c18d63efdbed1d8187f8b34e8b0810"
                },
                "time": "2013-05-15 11:26:02",
                "type": "project"
            }
        }
    }
}

satis.json

{
    "name": "My Repository",
    "homepage": "http://packages.example.org",
    "repositories": [
        { "type": "vcs", "url": ".git" }
    ],
    "require-all": true
}

try.sh

composer create-project --repository-url=packages.json test-vendor/test-project