FxCop is standalone tool that can analyse managed code assemblies. It gives report about improvement in code based on Microsoft standard coding guidelines. However you can also add your rules in this tool.
FxCop is not integrated into Visual studio. There is separate extension (FxCop Integrator ) which can integrate Fxcop in Visual Studio 2010.
How to Install
You can install FxCop Integrator as independent installer or as extension in Extension Manager.
How to Run Code Analysis ?