Sample COM Add-in code for Project Professional 2007
Please find below sample code (thank you Mike Shughrue) in C# for a Project Professional 2007 COM Add-in. This code is very similar to writing a COM Add-In Project Professional 2003. In the long term an easier way to start would be to leverage new next version of Visual Studio Tools For Office (VSTO): https://blogs.msdn.com/project_programmability/archive/2007/07/30/vsto-add-in-support-for-project-2003-and-project-2007.aspx