Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Voxel Range Threshold
ID_VOLUMETOMESH_THRESHOLDParameter: Use Absolute Value (ISO)
ID_VOLUMETOMESH_USE_ISOParameter: Surface Threshold
ID_VOLUMETOMESH_ISOParameter: Adaptive
ID_VOLUMETOMESH_ADAPTIVE_VALUEParameter: Create Curvature Map
ID_VOLUMETOMESH_CREATE_CURVATURE_MAPParameter: Curvature Direction
ID_VOLUMETOMESH_CURVATURE_DIRECTION