Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Selected Only
HAIR_TOOL_CUT_SELECTED
Parameter: Length
HAIR_TOOL_CUT_LENGTH
Parameter: Cut At
HAIR_TOOL_CUT_LINK
Parameter: Apply Cut Object
HAIR_TOOL_CUT_APPLY