To display a rear tool lathe in Axis, add BACK_TOOL_LATHE = 1 to your DISPLAY section in the ini file.
Information on rear/back tool display in LinuxCNC
The above image shows how the LinuxCNC tools should be shown for current tool orientations (as of 2.5.x). The front tool displays are the current orientations, the Back/Rear tool post is what it should look like if implemented properly. Also shown are arc directions when programmed and back plotted.
if LinuxCNC is ever to to be updated to follow Fanuc, Mitsubishi, Hass, or other larger industrial controls, the above is what should be implemented. Also shown are arc directions when programmed and back plotted.