Motors are wired up and functioning, I started with the Z-axis motor, which had to be converted from unipolar to bipolar following this guide: http://www.jangeox.be/2013/10/change-unipolar-28byj-48-to-bipolar.html

Next up is the X-axis motor, which worked out of the box on wiring up, though I had to set the stepper driver to the highest microstepping mode (1/16) since full step was very coarse. This axis may need to move to 1/32 microstepping if the steps are still too coarse for use on the highest magnification setting of 1000x.

Lastly the Y-axis motor was wired up, and I found the wiring was wrong; the correct order of the pins from left to right are A+ B+ A- B-. After swapping the two center wires the motor worked as expected. I ended up changing to another Y-axis motor since I bent the shaft trying to fit the slide on.

Here's a video of all 3 axes being exercised:

Next up I'll start designing the actual slide holder and bracket to hold the focus motor assembly.