如何重构：将一个类拆分为两个通过接口进行通信的类

I am just embarking on my first large-scale refactor, and need to split an (unfortunately large) class into two, which then communicate only via an interface. (My Presenter has turned out to be a Controller, and needs to split GUI logic from App logic). Using C# in VisualStudio 2008 and Resharper, what is the easiest way to achieve this? I am just embarking on my first large-scale ref