Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Objects
SLA_PROXIMAL_OBJECTSParameter: Exclude Parent
SLA_PROXIMAL_EXCLUDE_PARENTParameter: Include Subobjects
SLA_PROXIMAL_INCLUDE_SUBOBJECTSParameter: Use Vertices
SLA_PROXIMAL_USE_VERTICESParameter: Use Edges
SLA_PROXIMAL_USE_EDGESParameter: Polygon Radius
SLA_PROXIMAL_POLYGON_RADIUSParameter: Function
SLA_PROXIMAL_FUNCTIONParameter: Blend Mode
SLA_PROXIMAL_BLEND_MODEParameter: Start Distance
SLA_PROXIMAL_START_DISTANCEParameter: End Distance
SLA_PROXIMAL_END_DISTANCEParameter: Intensity
SLA_PROXIMAL_INTENSITY