The way I do it is to go vertical. Do a blender (roll left for 2 turns and go to the upper inside corners with the sticks). Then I start neutralizing the ailerons to get the flatspin flat. Right before the spin gets flat, hold the ailerons right there and switch the rudder over the other way. This method works on all my planes, but Im sure there are a few exceptions out there. You can take this and experiment with it and Im sure you get it sonner or later. Good Luck.