Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Lens Profile Filename
PH_LENS_PROFILE_FILENAMEParameter: Image Scale
PH_IMAGE_VIEW_SCALEParameter: Image Offset X
PH_IMAGE_VIEW_OFFSET_XParameter: Image Offset Y
PH_IMAGE_VIEW_OFFSET_YParameter: Texture
LENSDISTORTIONSHADER_TEXTURE