Following up on this answer to this question, I would like a clear, step-by-step set of instructions on how to set the application icon for a Qt application on OS X sufficient for distribution of the application via an installer and/or through the App Store.
The instructions should include how to set the four sizes of the icon, as referenced in the linked answer, above.
Please bear in mind that I have no experience in distributing OS X applications, building installers for OS X applications, or setting the icon that appears in the Finder bar for OS X applications. Rather, I am an experienced C++ programmer (mostly on Windows and Linux).
I especially seek a clear, step-by-step set of instructions.