Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Intensity
SPEC_INT
Parameter: Variation
SPEC_VAR
Parameter: Out of Range Type
SPEC_RTYPE
Parameter: Spectrum
SPEC_GRADIENT
Parameter: Use CD Effect
SPEC_CD_ON
Parameter: Width
SPEC_CD_WIDTH
Parameter: Peak
SPEC_CD_PEAK
Parameter: W Factor
SPEC_CD_WFAC
Parameter: Diffuse Intensity
SPEC_CD_DINT
Parameter: Diffuse Variation
SPEC_CD_DVAR
Parameter: Front Side
SPEC_CD_STYPE