Since dr dre didn’t respond to the original question, my response would be to use old school methods if VNAV was not available. You can approximate the descent point based on the 3-in-1 method or the metres button. eg From FL340 to sea level, 3x34=102NM, or FL340=10363m (103.63NM).
Nice try GBO but there are a few more considerations when manually calculating a ToD point. All you have done is demonstrate, once again, that you have NFI what you are talking about.