Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Samples
CHANLUM_SAMPLES
Parameter: Inital Offset
CHANLUM_OFFSET
Parameter: Sample Radius
CHANLUM_RADIUS
Parameter: Sample Type
CHANLUM_TYPE
Parameter: Stochastic
CHANLUM_STOCASTIC
Parameter: Gaussian
CHANLUM_GAUSSIAN
Parameter: Shadows
CHANLUM_SHADOWS
Parameter: Seed
CHANLUM_SEED
Parameter: Use Lights
CHANLUM_LIGHTS_MODE
Parameter: Lights
CHANLUM_LIGHTS