Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Radius
HAIR_LIVESELECT_RADIUSParameter: Visible Only
HAIR_LIVESELECT_VISIBLEParameter: Restrict
HAIR_LIVESELECT_RESTRICTParameter: Select Locked
HAIR_LIVESELECT_LOCKEDParameter: Shape
HAIR_LIVESELECT_SHAPEParameter: Pressure
HAIR_LIVESELECT_PENParameter: Aspect
HAIR_LIVESELECT_SHAPE_ASPECTParameter: Angle
HAIR_LIVESELECT_SHAPE_ANGLE