Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Mode
FP_SPLINEEMITTER_SPLINE_MODE
Parameter: Restriction
FP_SPLINEEMITTER_SPLINE_RESTRICTION
Parameter: Restriction Threshold
FP_SPLINEEMITTER_SPLINE_RESTRICTION_THRESHOLD
Parameter: Scatter
FP_SPLINEEMITTER_SPLINE_SCATTER
Parameter: Interval
FP_SPLINEEMITTER_SPLINE_INTERVAL
Parameter: Thickness
FP_SPLINEEMITTER_SPLINE_OFFSET
Parameter: Thickness Variance
FP_SPLINEEMITTER_SPLINE_OFFSET_VARIANCE