I don't know if Mach2 would be limited by anything in particular. Simply cut each thread as if it were a stand alone process. When you are ready to begin the next thread start, reposition your tool at a new Z position that is 1/4 of the lead ahead (or back) of the position you began the first thread at. Then, run the entire thread cycle again. Repeat until complete, for each start, moving your start point by 1/4 of the lead for each thread start.
Important note: do not change spindle speeds throughout the entire cycle, on a cnc
You can also use this method on a manual lathe, using the cross slide to advance the tool for each unique thread start.
Good luck