Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Color
SUNBURSTSHADER_COLORParameter: R Frequency
SUNBURSTSHADER_SCALE_RParameter: A Frequency
SUNBURSTSHADER_SCALE_AParameter: T Frequency
SUNBURSTSHADER_FREQUENCYParameter: Turbulence
SUNBURSTSHADER_TURBULENCEParameter: Radius
SUNBURSTSHADER_RADIUSParameter: Height
SUNBURSTSHADER_HEIGHT