If you have a stepper motor that works with the TB3 and has a plug for swapping cables, then it should work with spectrum. You will just want to swap out your TB3 cable with a spectrum motor cable, found here: http://https://emotimo.com/products/spectrum-stepper-motor-cables
We do not have a quick solution for motors with fixed wiring and a TB3 molex connector. We will offer a jumper cable for the spectrum in the future, like to we did for the TB3 to help our DIY community integrate with these motors. We will also have a diagram on motor pinouts down the line as well.