Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Strength
MGREEFFECTOR_STRENGTHParameter: Selection
MGREEFFECTOR_SELECTIONParameter: Effectors
MGREEFFECTOR_EFFECTORSParameter: Position
MGREEFFECTOR_POSITIONParameter: Position Strength
MGREEFFECTOR_POSITION_STRENGTHParameter: Position.X
MGREEFFECTOR_POSITION_XParameter: Position.X Strength
MGREEFFECTOR_POSITION_STRENGTH_XParameter: Position.Y
MGREEFFECTOR_POSITION_YParameter: Position.Y Strength
MGREEFFECTOR_POSITION_STRENGTH_YParameter: Position.Z
MGREEFFECTOR_POSITION_ZParameter: Position.Z Strength
MGREEFFECTOR_POSITION_STRENGTH_ZParameter: Rotation
MGREEFFECTOR_ROTATIONParameter: Rotation Strength
MGREEFFECTOR_ROTATION_STRENGTHParameter: Rotation.H
MGREEFFECTOR_ROTATION_HParameter: Rotation.H Strength
MGREEFFECTOR_ROTATION_STRENGTH_HParameter: Rotation.P
MGREEFFECTOR_ROTATION_PParameter: Rotation.P Strength
MGREEFFECTOR_ROTATION_STRENGTH_PParameter: Rotation.B
MGREEFFECTOR_ROTATION_BParameter: Rotation.B Strength
MGREEFFECTOR_ROTATION_STRENGTH_BParameter: Scale
MGREEFFECTOR_SCALEParameter: Scale Strength
MGREEFFECTOR_SCALE_STRENGTHParameter: Scale.X
MGREEFFECTOR_SCALE_XParameter: Scale.X Strength
MGREEFFECTOR_SCALE_STRENGTH_XParameter: Scale.Y
MGREEFFECTOR_SCALE_YParameter: Scale.Y Strength
MGREEFFECTOR_SCALE_STRENGTH_YParameter: Scale.Z
MGREEFFECTOR_SCALE_ZParameter: Scale.Z Strength
MGREEFFECTOR_SCALE_STRENGTH_ZParameter: Color
MGREEFFECTOR_COLORParameter: Color Strength
MGREEFFECTOR_COLOR_STRENGTHParameter: Color.R
MGREEFFECTOR_COLOR_RParameter: Color.R Strength
MGREEFFECTOR_COLOR_STRENGTH_RParameter: Color.G
MGREEFFECTOR_COLOR_GParameter: Color.G Strength
MGREEFFECTOR_COLOR_STRENGTH_GParameter: Color.B
MGREEFFECTOR_COLOR_BParameter: Color.B Strength
MGREEFFECTOR_COLOR_STRENGTH_BParameter: Weight
MGREEFFECTOR_WEIGHTParameter: Weight Strength
MGREEFFECTOR_WEIGHT_STRENGTHParameter: Modify Clone
MGREEFFECTOR_CLONEParameter: Clone Strength
MGREEFFECTOR_CLONE_STRENGTHParameter: Time
MGREEFFECTOR_TIMEParameter: Time Strength
MGREEFFECTOR_TIME_STRENGTHParameter: U Transform
MGREEFFECTOR_UParameter: U Strength
MGREEFFECTOR_U_STRENGTHParameter: V Transform
MGREEFFECTOR_VParameter: V Strength
MGREEFFECTOR_V_STRENGTHParameter: Visiblity
MGREEFFECTOR_VISIBILITYParameter: Visibility Strength
MGREEFFECTOR_VISIBILITY_STRENGTH