How do I get Xcode to replicate project group structure in the folder structure on disk?

I have an Xcode project with the following group structure:

ProjectName/
    Classes/
        class1.h
        class1.m
        class2.h
        class2.m
        ...
    XMLDocs/
        doc1.xml
        doc2.xml
        ...
    Resources/
        Info.plist
        MainMenu.xib
        ...

and so on and so forth.

I'd like this to be represented in the folder structure on the disk as well:

ProjectFolder/
    Project.xcodeproj
    Classes/
        class1.h
        class1.m
        class2.h
        class2.m
        ...
    XMLDocs/
        doc1.xml
        doc2.xml
        ...
    Resources/
        Info.plist
        MainMenu.xib
        ...

as opposed to the usual everything in the root project folder methodology.

Is there any way to do this without manually creating the folder structure on the disk and then having to repoint all the reference in Xcode to the new location?

Bonus points if you can tell me how to do this automatically any time I create a new group or add files to an existing group in Xcode.