You can configure Switcher to do this.
In Switcher's options, go to the Shortcuts section and click the Edit Shortcuts button.
In the Filter section, scroll down and select "Show Application Only." Add a new keyboard shortcut for Alt+`. Make sure you check Global shortcut. Select Activate when shortcut is Pressed and check End session when shortcut is released.
Now scroll down to Next Window in the Window section. Add a new keyboard shortcut for Alt+` (not global). Hit OK. You should now be able to press Alt+` to bring up Switcher showing only the windows of the foreground application, press ` to cycle to the next window, and release Alt to switch to that window.
Linked topic doesn't sound like it, but it actually also discusses cycling through an application's windows. – Daniel Beck – 2011-02-22T19:44:28.663
I would say that it is a duplicate of that question and according to that question...I'm not going to find a viable answer. – James P. Wright – 2011-02-22T20:07:20.183