It must be done on hard
It can best be done in training mode because you will get less points in olympic mode (even with perfects and perfect dismount i did not get a 16.xx)
I got it with mostly perfects 2 excellent i think but missed the last 4 on the dismount still got a 16.85
I had the controller between my knees in an upright angle so i could spam the triggers at max speed with my pointing finger getting a perfect all the time
Than its just getting the sticks under controll in that position
i got it first try this way