While I am not a big on going for triangle chokes, the reverse triangle is a powerful pinning position that lends itself to many submissions such as wrist locks, chokes, arm locks, and of course the Kimura.
This setup from the Kimura Trap is probably the easiest way of setting up a reverse triangle that does not require any flexibility to perform, or be a BJJ wizard like Braulio Estima to perform.
This was taken from my Kimura Trap System seminar at 10th Planet Bethlehem in Easton, PA