Set up a steaming device for this. The ideal thing is a wok with a steaming trivet. Put an inch or so of water in the bottom (enough so that it comes to just below the bowl), and put your bowl on the trivet.
Mix cornflour, sugar and soy sauce in a bowl. Add the chicken bits and ginger and stir well. Cover with lemon slices. Steam for 45 mins to 1 hour. Serve with some sort of vegetabley-ricey thing.