Here's my Chinese Elm... How does one go about air layering? Is it the same as any other plants species? Sphagnum moss, rooting hormone powder and wrapping?

Yes. Just the same as other species. Do not forget to girdle the bark too..
Do this once you see the buds breaking in spring or a little later. You will have roots in 6-8 weeks, normally.

You going to layer a semi-cascade?

That would be a good plan mate! Which branch?

GingerBonsai wrote: That would be a good plan mate! Which branch?

You could layer directly above the first branch?