Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Radius
HAIR_LIVESELECT_RADIUS
Parameter: Visible Only
HAIR_LIVESELECT_VISIBLE
Parameter: Restrict
HAIR_LIVESELECT_RESTRICT
Parameter: Select Locked
HAIR_LIVESELECT_LOCKED
Parameter: Shape
HAIR_LIVESELECT_SHAPE
Parameter: Pressure
HAIR_LIVESELECT_PEN
Parameter: Aspect
HAIR_LIVESELECT_SHAPE_ASPECT
Parameter: Angle
HAIR_LIVESELECT_SHAPE_ANGLE