Interfaceing C++ using a Win32 GUI

[BLS]

Hi,
I am porting a huge C++ Windows GUI into D1. (no fun at all) But I 
wonder if it  is possible to keep the original C++ lib using D2's new 
extern (C++) feature. Advantage is that I have less trouble regarding 
the win header files, and I guess this approach will require less time.
BUT - I wonder how to manage the windows callbacks :

C++
BOOL CWnd::RegisterClassEx(WNDCLASSEX& wcx)
{
wcx.lpfnWndProc    = /CWnd::StaticWindowProc/;
....
if (!::RegisterClassEx(&wcx))
....
}

static LRESULT CALLBACK StaticWindowProc(HWND hWnd, UINT uMsg, WPARAM 
wParam, LPARAM lParam);

Of course this function has to be within the D code as
extern (windows) static ..., because we need to manage the eventhandling .

Mission impossible, good/bad idea, what do you think ?
Bjoern