For composer.json, it has actually recently changed to:

``` json
    "extra": {
        "component": {
            "scripts": [
                "ember.js"
            ]
         }
    }
```

Currently, Component Installer won't merge multiple JavaScript component JavaScript files into one, but that should be in within the next couple days. I've put together an issue for that to track it:
https://github.com/RobLoach/component-installer/issues/17

Thanks again @baldurrensch! This is lookins great.