Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Override Group
SKY_CLOUD_OVERRIDE_GROUP
Parameter: Active
SKY_CLOUD_GENERATOR_FLAG
Parameter: Mix
SKY_CLOUD_MIX
Parameter: Altitude
SKY_CLOUD_ALTITUDE
Parameter: Falloff
SKY_CLOUD_FALLOFF
Parameter: Luminance Falloff
SKY_CLOUD_LUM_FALLOFF
Parameter: Transparency Falloff
SKY_CLOUD_TRANS_FALLOFF
Parameter: Color
SKY_CLOUD_COLOR
Parameter: High-Quality Lighting
SKY_CLOUD_HQ_LIGHTING
Parameter: Falloff
SKY_CLOUD_OBJECT_FALLOFF
Parameter: Distance
SKY_CLOUD_OFFSET_DIST
Parameter: Keep Shape
SKY_CLOUD_KEEP_SHAPE
Parameter: Cloud Type
SKY_CLOUD_TYPE
Parameter: Coverage
SKY_CLOUD_COVERAGE
Parameter: Contrast
SKY_CLOUD_CONTRAST
Parameter: Ratio
SKY_CLOUD_SIZE_RATIO
Parameter: Groove Depth
SKY_CLOUD_GROOVE_DEPTH
Parameter: Shape Strength
SKY_CLOUD_SHAPE_STRENGTH
Parameter: Scale
SKY_CLOUD_SCALE