I suggest practicing the omelette by itself first and as often as you can.
Cooking chopsticks are a must, get the pan hot enough and work quick, stirring the omelette quick to the right consistency, then letting it set on the outside and flipping/rolling in the pan to seal it.
You'll need learn the flipping technique where you flick the pan up and then knock it down quickly by hitting down on the handle. This is what let's the omelette get it's first and most important rotation.
It's a muscle memory thing, but like anything, you can and will inch closer to the technique.
Once you have the omelette moving around in the pan the way you need, it's a matter of getting the timing right so that each part of the omelette is cooked right. Roll the omelette onto a plate- it should be able to roll side to side on the plate without breaking but still be loose and creamy on the inside, like so: https://m.youtube.com/watch?v=XBZSRub2qhQ.
The famous chef in Kansai that's known for these is seen using both carbon steel omelette pans and nonstick - I suggest a mid-weight nonstick omelette pan; no reason to make things more difficult upfront.
Once you've got the omelette down, then you can start bringing in the rice and demi glacé.
The rice molds are called "melon omurice molds" and you can sometimes find them available from Japan online. (Amazon - https://www.amazon.com/SHIMOTORI-Omurice-mold/dp/B01M64TIWL)
One last tip - I found it useful to watch someone who wasn't a renowned professional pull it off: https://m.youtube.com/watch?v=eeeTvatu6fk
Good luck - took me 6 months and I'm still not great :)