Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Override Group
SKY_CLOUD_OVERRIDE_GROUPParameter: Active
SKY_CLOUD_GENERATOR_FLAGParameter: Mix
SKY_CLOUD_MIXParameter: Altitude
SKY_CLOUD_ALTITUDEParameter: Falloff
SKY_CLOUD_FALLOFFParameter: Luminance Falloff
SKY_CLOUD_LUM_FALLOFFParameter: Transparency Falloff
SKY_CLOUD_TRANS_FALLOFFParameter: Color
SKY_CLOUD_COLORParameter: High-Quality Lighting
SKY_CLOUD_HQ_LIGHTINGParameter: Falloff
SKY_CLOUD_OBJECT_FALLOFFParameter: Distance
SKY_CLOUD_OFFSET_DISTParameter: Keep Shape
SKY_CLOUD_KEEP_SHAPEParameter: Cloud Type
SKY_CLOUD_TYPEParameter: Coverage
SKY_CLOUD_COVERAGEParameter: Contrast
SKY_CLOUD_CONTRASTParameter: Ratio
SKY_CLOUD_SIZE_RATIOParameter: Groove Depth
SKY_CLOUD_GROOVE_DEPTHParameter: Shape Strength
SKY_CLOUD_SHAPE_STRENGTHParameter: Scale
SKY_CLOUD_SCALE