I’m potentially doing this in one of my courses under development using simulation. You could do it with pure Lectora actions and screen shots. It would be a good amount of Show/Hide clicks and carefully placed buttons. You can set variables to track each click to make sure they complete each action (open browse window, select correct file, click ok, etc).
If I create my simulation for attaching/opening a file, I can post it so you can get an idea of how I would do it.