Stitchmap Kit and UVs to Mesh
Use the Stitchmap Kit to easily create stitching on complex or deformed meshes. The UVs to mesh function in Modo gives you a flattened out version of your mesh, on which you can lay down your curves, use the Kit to create your stitching, and then bake out to use use the result on your original item.
Stitchmap Kit is available on Gumroad https://gumroad.com/l/stitchmap