Hey SteveS7,
in the controller, it would be simple. You can assign motor 0 to Y and motors 1 and 2 to X (with “reverse” selected). But if you have a Journeyman, your machine would no longer be a 48"x32" machine, but a 32"x48".
As for postprocessors, there is a different one for each CAM software. It would need to be adapted to reflect the dimensions.