This is something I'm sure thousands (if not millions) would love to do. To be able to click a flat ride, click the control button and be able to press keys on your keyboard to open/close the harnesses, lower/raise platforms, rotate the ride and control the strobe lights etc... All this with real-time physics. But when the user stops controlling the ride, it resumes with the default animations, as if someone else is controlling it.
Even if this isn't a possible feature by default, at least give us the possibility to add mods to be able to do this.