Web Workbench Introduces Sass, LESS, and CoffeeScript to Visual Studio 2010
Mindscape recently announced Web Workbench, a new extension that adds Sass, LESS, and CoffeeScript functionality to Visual Studio 2010.
If you only want Coffee Script, or only wanted to use Less, then by all means just use those parts. It's all in one install but there's no reliance on each other in your applications.
Web Workbench is available for free from the Visual Studio Gallery, or can be installed via the Visual Studio Extension Manager.