At least one machine has been packed into suitcases in this fashion and shipped successfully (sans wasteboard).
There is some additional packaging in the box which should be workable for using to package things. You could also cut up the outer boxes --- there's a over-wrapper box as well as a nifty pair of nesting top and bottom which make the inner box.
Wrap the extrusion well and carefully --- put the two matching pairs together and put the sides with the V-rails on the inside. Wrap the long X-axis one up w/ a couple of extra layers of cardboard and additional packaging around the V-rails.