如何将自定义“项目项节点”添加到Visual Studio Flavored Project

I have written a simple flavoured project for Visual Studio 2008, and I want to add a custom 'folder' item to the solution explorer, similar to the 'references' folder. This folder will contain more 'custom' nodes, which dont actually represent files, but in-memory objects. How do I hook into what is displayed in the solution explorer? I cant seem to find any simple code examples.I have written a simple flavoured project for V