Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Display
ID_MG_TRANSFORM_DISPLAYMODE
Parameter: P
ID_MG_TRANSFORM_POSITION
Parameter: R
ID_MG_TRANSFORM_ROTATE
Parameter: S
ID_MG_TRANSFORM_SCALE
Parameter: Color
ID_MG_TRANSFORM_COLOR
Parameter: Weight
ID_MG_TRANSFORM_WEIGHT
Parameter: Time
ID_MG_TRANSFORM_TIME