Certainly. Create a new screen, call it "pre-tourney" or something so you can distinguish it from the main screen that you display to your players. With the new screen selected, press "Copy Screen" and then select your main screen. Now you have two screens that are exactly the same - one to display during the tournament, and one to display before the tournament. With your pre-tourney screen selected, press the "Background" button and set the background image. Make sure to check "Override all backgrounds" and/or "Override all borders", whichever are appropriate for your screen.
Press the "Screen Sets" button. Press the "New" to create a new screen set. Again, call it "pre-tourney" or something similar. Press the "Add" button and add the "pre-tourney" screen to it. Press the "Conditions" button to set the conditions of the screen set. In the "Stage" section, select "Before Game".
Done. Make sure to save the layout so you can use it in future tournaments.