In this trick every throw from one hand is made Over the top, whilst every throw from the other hand is thrown underneath just like in a regular cascade. In this pattern all the balls follow each other around in the shape of the edge of a boomerang.
For a right hand half shower, every right hand throw is an over the top throw, so the right hand always uses outside scoop & the left hand uses inside scoop.
The rhythm for this is still the same even 'left, right, left, right...' used in the cascade. You may find yourself falling into a synchronous (both hands throw together) or lopsided throwing pattern, just throw one ball a little higher than normal, wait for it to peak & then throw the next ball to get back into an even rhythm.
Again, practise this on both sides.