Dominique mocheaneua performed that in 96, I havent seen it since! I would actually almost try a messed up cartwheel, where landing on your shoulders, would be the goal, while wrapping your arms around the beam. And then when you rotate to the other direction, just shift your weight to your opposing shoulder. Hope that makes sense, and I hope it helps! And if I am WAY off base, then by all means coaches, chime in!
I had a teammate who did this mount in college. I am not sure how she learned it but I have tried it before. I would say to start by just getting in the first position (with arms behind you around the beam) and have someone hold you there until you felt comfortable. Then try the cartwheel part into it. It's tricky and you'll have to find the way that works for you but definitly use a spring board so you get some extra lift. Most of this skill is done by trial and error. Try both left and right sides and have someone help initiate the turns at first. Eventually you'll get it. Good Luck!
Yes, Dominique did that element and it's very cool. I love seeing unique elements that are rarely performed. It seems too many routines these days use the same elements at every level and that makes what should be an exciting sport rather dull. Does anyone else feel the same way I do?