I think hWnd is an unsigned int not a pointer.
Anyway I think I have found a solution. I have been converting the
sip.voidptr into a string using str() wich was wrong. It resulted in
the string <sip.voidptr object at 0x00B7C0A0>.
This is what I have passed to Ogre as render window. Ogre
understandably refused to render into this non existing window :). But
when I convert the pointer into an int using int()
I think I'm getting the real Windows winId wich is in my case at the
moment 854498.