VSPackage: How to create a custom virtual node like References node

Question

Hello, I have a C# flavored project and I want to add some custom nodes to my project where the only options when you right click on them is to add or remove a custom project item that I have already created, so I want it to be like the References node in that it cannot be deleted renamed and it only has 2 context menu options. Any idea or links on how to do something like this would be greatly appreciated.

Thanks

Kenny Chinn