Terrain features sculpting in cryengine?

NAIMA

Hi I have theneed to sculpt a terarain feature outside of the editor and then eventually reimport as a voxel , this is because I want it to perfectly stick seamlessly in the ground without seams and texture it with the texture terrain tools , more over I want to export also the texturing of it into outside source be able to rework and reimport retextured , how can I do that?

Let's say that I want to create a mount rushmore style thing how should I do ?