Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Blur Offset
SHADER_MIPOFFSETParameter: Blur Scale
SHADER_MIPSCALEParameter: Override Defaults
SHADER_GPUTEXENABLEDParameter: Texture Size X
SHADER_GPUTEXSIZEXParameter: Texture Size Y
SHADER_GPUTEXSIZEYParameter: Texture Bit Depth
SHADER_GPUTEXBITDEPTH