Through the console, it's a renpy command. The list of scenes needed for specific stars is under scripts/progression. You need to decompile the game with unren first, obviously.How does one doFrameChange? or know which are the right events to check off?
note: you won't trigger the whole scene this way, it's just a way to mark an unreachable event completed. Ideally you want to make sure the triggers can't be reached at your current game state by actually reading the scene script first. Granted, many of the event variations are not progression-critical.