Well, lets say your in a knife edge flight from left to right, you will only be using left rudder to hold your altitude. Cut your throttle to idle and as it slows down keep adding left rudder to hold it in knife edge. Once it pretty much stalls, add full left aileron, full down elevator and full left rudder. It will tumble a sec then should go into the spin, give a bit of throttle to spin it up a bit.

Then the flat spin entry is simply hold all sticks where they are, and add full right rudder then slowly reduce the aileron as necessary.

Hows that?