Check out my feature request for more on this https://forums.zwift.com/t/add-terrain-mode-option-to-workouts-especially-great-for-kickr-climb/14694?u=chip_brunk but I’d do my hard intervals when climbng just like I do structured workouts outdoors. Between the Workout “Pause” button and the ability to turn around with the arrow key/button it would be pretty easy to control but does require you know a little about the course you are riding.