Rearward CG should help.

As for the stick movements, I'm not sure I would explain it that way - for inverted flat spins, the aileron and rudder should start off reversed. Then as you add power, the aileron is moved toward neutral, and in some cases (some planes) you must go past neutral and end up with ailerons and rudder in the same direction to flatten it out. But if you don't cross the rudder and aileron first, I think in most cases you'll more probably end up in a knife edge spin.

I think most planes flat spin left better than right. Here are my stick movements for inverted left flat spin. I guess its more of a blender really:

Enter vertical dive at low speed and throttle. Add full left aileron to start rolling. Do 2 rolls, add full down elev at the same time you add full right rudder. It will be in a weird spin. After a bit of that, simultaneuously and slowly add power and shift the aileron towards neutral (while holding full down elev). Again, the final location of your aileron input (and throttle) depends on the plane. Some require full opposite aileron to really flatten out. I find my aileron ends up about 75% past neutral for my UCD.

There is a good description of how to do an UPRIGHT flat spin on p. 38 of the March 2004 issue of Fly RC magazine. The only difference for upright flat spins is up elev instead of down.

Hope this helps.
K