Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Intensity
SPEC_INTParameter: Variation
SPEC_VARParameter: Out of Range Type
SPEC_RTYPEParameter: Spectrum
SPEC_GRADIENTParameter: Use CD Effect
SPEC_CD_ONParameter: Width
SPEC_CD_WIDTHParameter: Peak
SPEC_CD_PEAKParameter: W Factor
SPEC_CD_WFACParameter: Diffuse Intensity
SPEC_CD_DINTParameter: Diffuse Variation
SPEC_CD_DVARParameter: Front Side
SPEC_CD_STYPE