RhinoCommon:
to be updated:
CreateTrimmedSurface or CopyTrimCurves may be what you are looking for
M_Rhino_Geometry_Brep_CreateTrimmedSurface.htmM_Rhino_Geometry_Brep_CopyTrimCurves.htmKeep tracking the new release of RhinoCommon for the Brep attributes for additional parametric control.
Rhino 4.0 .NET SDK:
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OnBrep copyTrimmedPattern(OnBrep source, OnSurface target)
  {
      OnBrep brep = new OnBrep(source);
      if((brep.m_F.Count() == 1) && target != null)
      {
          OnBrepFace face = brep.m_F[0];
          OnSurface surface = target.DuplicateSurface();
          int index = brep.AddSurface(surface);
          face.ChangeSurface(index);
          if (brep.RebuildEdges(ref face, 0.001, true, true))
          {
              brep.CullUnusedSurfaces();
          }
      }
      return brep;
  }
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2010 0810 CopyTrim:
