Your title mixes a goal -- exposing more of the MSI api -- with a particular means -- exposing an object that is only useful with ctypes. So I have taken the liberty of removing the implementation limitation. While clever, I do not believe that strategy has any precedent in the stdlib. While the stdlib includes ctypes, it does not use it to implement functions. While your proposal does not directly use ctypes, it does indirectly, by proxy (the user). So I think wider discussion, perhaps on pydev or python-idea, to see where the proposal falls with respect to current policy, before it could be approved. A special feature of msilib is that it is Windows only, where ctypes *should* always be available (though even that is not guaranteed if there is no maintenance, which there mostly is not at present).

Martin's suggestion is the traditional path. I have 0 knowledge of MSI API. How many new functions are we talking about? 10? 100?