ZrushCore has not the function grap objects to alpha, also I searched an other way. My Solution:
A) Create a model of the stitch in blender.
B) Bake the displacement map of the stitch to a plane.
C) Edit the displacement map to a brush alpha in photoshop.
D) Import the alpha to ZbrushCore.
E) Adjust the brush parameters.
F) Draw the stitch in ZbrushCore.
The blender model of the stitch:
The blender model of the stitch with the plane as bake target:
Here you can measure the bias and the ray distance (distance=3; bias=0.15):
Select all objects, but the plane as last object, so it is the active object and bake the displacement map:
In photoshop: Colour to gray values; invert the gray values; colour value correction automatically.
Copy the upper half to the lower half and retouch the middle line. So it is seamless at the top and the bottom. With the colour black mask the edges of this picture, but not the areas at the top and bottom, in wich the rope is.
In ZbrushCore import the alpha: Alpha->Import. Select the standard brush, and choose the imported alpha. Enable lazy mouse and adjust the lazy steps, so that a stich is beside to the next stitch. Click with the mouse at the start point or touch at this place on the grafic tablet with the pen. Then press shift and pull the green line to end point. Let go the shift key, and the stitch is drawn.
And this is my result