Disable the "New Item" context menu item on specific folders

Hi!

I have an isolated visual studio shell (vs 2012). There is a project system in place and now I would like to disable the "New Item" command if the user has selected a specific folder or a project. Is this possible? I tried to get the command with creating a OleMenuCommand object with the guid of the command. After that I added the BeforeQueryStatus handler to it. But it doesn't get called. So I think it has something todo with the fact that this command is not a dynamic command.

Is there another way to that, which I couldn't find in the documentation?

Regards

Manuel