I wired mine as two back to back switches with two DZ-2500C machines along with the two DZ-1008 being used to switch power to rails 1-4 depending on the direction of each switch. So each switch with its corresponding DZ-1008 flips the power on/off to two(2) of these rails.
The ross diagram for DZ-1000s was confusing when using the DZ-2500Cs.
As far as non-derailing I used the yellow and green wires of each DZ-2500C wired to the inner short rails on each end of the side that the DZ-2550C was controling.