I don't run Techo's software, but do believe we approach things identically in terms of motion. That being said, you also need to flip the homing direction and not just scaling to negative. In my own software, it's an INI file flag, but I think for theirs it's a menu option. Unlike techno's method in terms of homing, X and Y are homed at the same time, after Z is homed but the logic is just the same. Look for Homing direction and flip that as well.