As a plugin of the month, the download includes the source code. The source code: gets installed to a "Source" folder beneath the plugin's installed location, has been provided as a Visual Studio 2010 project containing the C# code, but is not required to run the plugin. The source code is provided to inspire would-be developers to see how easy it is to extend the functionality of AutoCAD.
So please share your stories of success or failure using the plugin with us at firstname.lastname@example.org. We'd only be especially thrilled to hear if you have extended the application by modifying the source code.
BIM searching is alive in the lab.