Archicad's mesh cannot read xyz coordinates automatically. To do that function requires Cigraph's Archicad Add-On "ArchiTerra."
Archicad's mesh CAN be plotted and elevated using XYZ coordinates, but only point-by-point. This is quicker than it seems, especially if you learn to ignore unimportant points and focus only on critical ridges and plateaus.
Your question implies that you would like contours [3D curves] and Archicad cannot do this function, either - to convert elevation points into contour lines.
But who cares since contours are useless abstractions.
Archicad likes a DWG or other electronic layout of the site. It can then quickly follow contours to translate upward into a 3D volume. This is your quickest method.
Dwight Atkinson