Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Texture
XRAIN_SHADERLINKParameter: Direction
XRAIN_DIRECTIONParameter: Intensity
XRAIN_INTENSITYParameter: Smoothness
XRAIN_SAMPLESParameter: Weighting
XRAIN_WEIGHTEDParameter: Clamp UV coords
XRAIN_CLAMPParameter: Intensity Shader
XRAIN_WEIGHTSHADER_LINKParameter: Strength
XRAIN_WEIGHTSHADER_INTENSITY