Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Selected Only
HAIR_TOOL_CUT_SELECTEDParameter: Length
HAIR_TOOL_CUT_LENGTHParameter: Cut At
HAIR_TOOL_CUT_LINKParameter: Apply Cut Object
HAIR_TOOL_CUT_APPLY