Hi Jeff,
State machine r0.5 uses a slower communication speed by default, so you'd have to mod the firmware.
The bigger issue is RS-485. The UART channels are translated to RS-485 for robustness at high data transfer speed over the twisted pairs of the CAT5 cable. You'd need to connect this IC (plus a power supply decoupling capacitor) to the state machine. Correct wiring is shown in the Eagle files for the r0.9 PCB, here. State machine side power for the IC should be Arduino's 3.3V supply pin.
I hope this helps!
-Josh
