My thinking on this is that you want the material to move in such a way as the cutter cut as if it was machining on the normal X or Y axis.
So if your A is in line with the X you are replacing the Y axis, if + moves are away (tool movement) from the front of the machine then the top of the stock would need to rotate towards you, anti clockwise if the rotary is on the left of the table.
Basically as the diagrams have shown.
Steve