No.
A) Microsoft Windows XP and earlier: The SetWindowLongPtr function fails if the window specified by the hWnd parameter does not belong to the same process as the calling thread.
B) What did you think setting the app's HINSTANCE is going to do? I don't know what it would do. I wouldn't think it would do anything. It's not like it would rebase the app or anything, much less do anything to help the the remote window closing sitch.
