Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Reference
GV_HAIR_POINT_OBJECT
Parameter: Mode
GV_HAIR_POINT_MODE
Parameter: On
GV_HAIR_POINT_INPUT_ON
Parameter: Guide
GV_HAIR_POINT_INPUT_GUIDE
Parameter: Index
GV_HAIR_POINT_INPUT_POINT
Parameter: Segment
GV_HAIR_POINT_INPUT_SEGMENT
Parameter: Segment Delta
GV_HAIR_POINT_INPUT_T
Parameter: Position
GV_HAIR_POINT_INPUT_SET_POS
Parameter: Dynamic Position
GV_HAIR_POINT_INPUT_SET_DYN_POS
Parameter: Velocity
GV_HAIR_POINT_INPUT_SET_VELOCITY
Parameter: Mass
GV_HAIR_POINT_INPUT_SET_MASS
Parameter: Add Force
GV_HAIR_POINT_INPUT_ADD_FORCE
Parameter: Position
GV_HAIR_POINT_POINT_VEC
Parameter: Tangent
GV_HAIR_POINT_POINT_TANGENT
Parameter: Velocity
GV_HAIR_POINT_POINT_VELOCITY
Parameter: Mass
GV_HAIR_POINT_POINT_MASS
Parameter: Force
GV_HAIR_POINT_POINT_FORCE