I suppose you could build a machine that could emulate hand engraving. You'd need to make a holder for a graver that would rotate according to the direction of the lines it was cutting; a rotary axis parallel to Z could do that, probably using a rotary table with a planetary gear where the spindle normally is mounted. You'd need specialized CAM software, though, that could analyze each letter or line you want to cut and command the rotary axis to keep the graver perpendicular to it while tracing the letter in X and Y and changing the height in Z to control the depth of cut and line thickness. It's possible that software like that exists, although I've never heard of it. If not, maybe you could find someone to write it for you.