Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Evaltime
SPIN_INTENSParameter: Time
SPIN_TIMEParameter: Variation
SPIN_TIMEVARParameter: Phase
SPIN_PHASEParameter: Variation
SPIN_PHASEVARParameter: Friction
SPIN_FRICParameter: Speed Dependence
SPIN_SPEEDDEPParameter: Size Dependence
SPIN_SIZEDEPParameter: Axis Type
SPIN_AXISTYPEParameter: Axis
SPIN_AXISParameter: Variation
SPIN_AXISVARParameter: On
IN_SPIN_ONParameter: Animation Time
IN_SPIN_ATIME