Hello! I do it manually in Blender, i just use the Smart UV Project tool. This works perfectly for ‘normal’ meshes, but for clothing (since there’s a lot of foldings) I have to manually check that there’s no UV overlap.
And then I just bake the lights to see if the meshes are working correctly in order to be ready for my project and for the marketplace. But yeah it’s very time consuming, I don’t know much about scripts, do you mean inside UE4 or in some modeling program like 3ds Max or blender?