Global System Hook (dll) and connect via VB.Net

Hello!
For weeks now, I have been researching system hooks and messages; but
with little return. :-(

My end goal is to hook into the Global File Open/Save dialog box, add a
button to it, and when the user click on the button to enable a vb.net
form. The form will need to interact with the path of the dialog box.

I believe I can find out how to add the button, but I'm having a real
problem finding source for creating the native dll to hook in. (nearly
all global hooks are not natively supported in the .Net framework.)

If someone knows of a dll and source, please let me know... to get an
idea, directfolders can give you an idea. (different type of app.)
http://www.codesector.com/directfolders.asp

Thanks so much!

Oh, below was the closest I've found to being a complete .dll but it
doesn't work:
http://groups.google.com/group/microsoft.public.win32.programmer.kernel/browse_thread/thread/4d14199f7850d0c3/3c9f5cc60bf1d003?lnk=st&q=&rnum=4&hl=en#3c9f5cc60bf1d003

I tried to get in contact with the author, but email addy was bad.