Thank you for your patience with me. Can you explain the relevant console commands?
No problem 
Avanar gave you three very useful commands and you also clearly know how to use the "size" command, so I won't go over again.
That leaves the "rotation" command; it's used like the "size" command with the same parameters: "rotation 90 0 0" allows, for example, a 90° rotation on the X-axis, and "rotation 90 90 0" a 90° rotation on both X and Y axes.
In a more pragmatic way, you position your block in modular snapping on a chosen snap point without placing it, you enter the command, the block flips, and then you can place it. Nothing more. Of course, the choosen snap point is the center of rotation.
However, be careful with this command: the rotation is absolute, meaning its parameters are only true for a block to which you haven't previously applied another rotation. Think to push BACKSPACE key first if you have any doubt.
