Correctly displaying the 4th axis is not all that hard. What you want to do is under the "config" pull down menu choose toolpath. Then select under rotations A-Rotations Enabled. Under Mach3's setting tab or alt-6 set the diameter of the part for the A axis in the top right corner Called Rotation diameter so that Mach can display correctly. Now regenerate your tool path. If A axis is used and your setup is correct it will display. I use this as a good way to see if my spacing is correct. It will also show if any major errors are there.
good luck.
Jim.