Sorry, I haven't been on this site for a very long time. I have the same machine, No9 if its interessant. I have seen, the stepper drivers work with 5V-TTL and Step-dir like many normal stepper drivers.
Unfortunately, I don't know which gear ratio they use for the wormgear.
If you remove the ratchet and change it to a wheel with a Bicycle Brake or similiar, it should be no big problem, to use it bidirectional. But you must use the brake to clamp your rotary table.