If they are analogue drives then you will need some sort of convertor to turn the Step/Dir signals from Mach into +-10v for the drives. There used to be the Pixie boards that would do that but afraid they are no longer made, Rutex make some but have not seen any reports as to whether they work well or not.
Another option would be use an external motion controller such as the DSPMC or Galil, they are not a cheap route though

DSPMC seems to be working well and from what I have heard the Galil seems to be progressing as well.
Hood