As Macona says, the Mitsu servos work fine on 5v level step and direction signals for position control. Obviously, if you wish to use one in 'speed' mode, you need a 0-10v signal, so any board that works with a VFD will work (eg. Digispeed).
What it might pay you to do is make breakout boards for the cables that plug into the servo using the 20 pin 3M connectors. There are 20 wires in each of these and there are two connectors per servo axis. The majority of these 20 wires will not need to go to the PC/Mach BOB.
Similarly, it might pay to set up suitable RS422 boards etc so you can use the MR-J config software in a painless manner (using RS232 means you can only look at one axis at a time and have to physically change cables to look at a different one).
If you need any detailed help setting them up, please ask.