Try it stock first -- every plane is a bit different. You will have to fiddle with your entry attitude & entry speed as well. My Seamaster prefers a slightly inverted entry. You will also need absolutely max aileron & rudder throws, but be carefull with the elevator. The Seamaster ARF can snap violently nose-down-inverted if you have too much elev throw & jam it on all at once.

If you get it right, the plane will tumble end-over-end, while rolling. Very violent, & the exit is also noteworthy -- a power-on inverted spin. Don't keep it in the inverted power spin or it could go flat, especially if you let the ailerons fall to neutral. Recovery is throttle closed & hands off until it stabilizes in a vertical dive (2 - 3 turns). Until you get used to it, you should have a minimum of 200' altitude at entry. The first few times you try it, the pucker-factor is 10/10.