It's actually a pretty easy trick if you can already rodeo. People like T-Wall and TJ Schiller do them well because they make the two tricks look different. Some people do the exact same trick and just don't go inverted, which in my opinion is pretty lame.
I started trying flats the way T-Wall does them and I think they look better and are way more fun and comfortable. Try taking of similar to a rodeo, but think about looking around your leading shoulder as long as possible to prevent rolling onto your back. That's what helped me.
"For me, my family, my friends and skiing, that is for me. That's my life. The joy I get from skiing... that's worth dying for." - CR Johnson