If the braces that form the x are cut to create a half lap then they should assemble easily and be in the same plane, that is flush surfaces on both sides. Cut the tenons on the ends similar to regular brace tenons and the mortises cut be cut to fit these tenons.
As this is a table and not hooked to any concrete foundation you could just slide the legs onto the pre-assembled x from each side.
I don't see it as a problem, other than the weight of the legs.
You could make a scale model to perfect assembly procedures.
Good luck with your project.
Jim Rogers