Click to cycle through open instances?

When multiple instances of a single application are running, left-clicking the icon will cause Plank to show/hide all instances on the current workspace. Is there a way to change this behavior so that it will instead switch focus to the next instance of that application? The behavior I'm interested in is what Windows does when LastActiveClick is set true in the registry.
http://www.howtogeek.com/howto/16334/make-the-taskbar-buttons-switch-to-the-last-active-window-in-windows-7/

Based on the responses to question 233055, I'm guessing this will require modifications to the source code. Any tips/suggestions would be appreciated. Thanks.