Of course this process is used only when it's convenient and easier to model this way rather than modeling from scratch in Max, but a lot of the props were still just modeled the old box modeling way.
And here's the full character already retopologized and ready for UVs (Fig.07 - 09).
UVs in Max
The third step was to have its UVs ready. I worked on all that in Max and at the end I separated him into eight UV shells: head, cloths, torso, arms, legs, boots, props and engine (Fig.10). Each one was meant to have a 4k texture.
With the character already modeled and UVs ready, I then exported each of the eight parts as OBJs back into ZBrush, and created a ZTL file for each one for later ZBrush detailing.
Sculpting Details in ZBrush
Here is where I put some more specific details I wanted for the character, like scratches, rust and prints on the metal; stitches and wear on the leathers; veins and wrinkles on the skin, etc. There are some details I prefer doing later while texturing, like tears (using opacity maps), leather wrinkles (using bump maps) and cloth bumps, etc. I think it's easier and faster to create these kinds of details later rather than sculpting them in ZBrush. The following images show some ZBrush sculpting examples I did for this guy. Head scratches and prints on the metal (Fig.11).
Cloth folds, wrinkles and stitches (Fig.12)