converting JS to CS, what is @script

How do I convert this to CS?

@script AddComponentMenu("Camera-Control/Mouse Orbit")

its from the MouseOrbit.js

It's called an Attribute.

[AddComponentMenu("Camera-Control/Mouse Orbit")]

It goes on your class, or your field/method in your class that you want to modify. In this case, it goes on the class:

[AddComponentMenu("Camera-Control/Mouse Orbit")]
public class ...

http://msdn.microsoft.com/en-us/library/aa288454(v=VS.71).aspx

There is a Converter from M2H Studios for this, you can convert UnityScripts written in JS to C# http://m2h.nl/files/js_to_c.php