To complete my question. My modification of the axidraw.py so far (lines 158/9 and 2174/5):
motor_dist1 = delta_x_inches
motor_dist2 = delta_y_inches
delta_x_inches_rounded = motor_dist1_rounded
delta_y_inches_rounded = motor_dist2_rounded
and of course adapting the plotting area in the config file..
Is there any other element of the code that needs modification (especially when printing a svg-file) using another setup/axes-movements?