Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Weight
FALLOFF_STRENGTHParameter: Size
FALLOFF_SIZEParameter: Scale
FALLOFF_SCALEParameter: Offset
FALLOFF_SHAPE_OFFSETParameter: Orientation
FALLOFF_SHAPE_AXISParameter: Slice
FALLOFF_SHAPE_SLICEParameter: Radius
FALLOFF_SHAPE_TORUS_RADIUSParameter: Spherical Falloff
FALLOFF_FUNCTION_SPHERICALParameter: Outer Radius
FALLOFF_FUNCTION_RADIUSParameter: Falloff
FALLOFF_FALLOFFParameter: Falloff Function
FALLOFF_FUNCTIONParameter: Clamped
FALLOFF_CLAMPEDParameter: Spline
FALLOFF_SPLINEParameter: Spline Animation Speed
FALLOFF_ANIM_SPEED