Apply X-offset to gcode (re-slicing not possible)
You can use G92 to change the coordinates the machine "thinks" it's at. If just after homing, you apply

G92 X-10


the machine now thinks it's at X = -10, while in reality it's at X = 0. This results in everything thereafter behaving as if it is shifted in the positive X direction by 10 mm (since if you then commanded a move to X = 1 the machine would move to what is physically X = 11).