I am not sure what the answer would be, other than getting a breakout and wiring them directly as the Stepmaster has no provision for that.
I really came here to say you really should not bother with the Stepmaster. You will just be wasting time, materials and ensuring a lot of grief. They were notoriously bad, even in their day, and things have come even further since then. Unfortunately their bad reputation was richly deserved. It really just isn't suitable for driving a Taig. Sorry.
i would suggest getting something newer, many drivers now already have breakouts and such built in anyway. No reason throwing good money after bad getting a breakout for that thing.