Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Operator
VP_TONEMAPPING_OPERATOR
Parameter: Scale
VP_TONEMAPPING_SCALE
Parameter: Exposure
VP_TONEMAPPING_EXPOSURE
Parameter: ISO
VP_TONEMAPPING_SENSITIVITY
Parameter: F-Stop
VP_TONEMAPPING_FSTOP
Parameter: Gamma
VP_TONEMAPPING_GAMMA
Parameter: Pre-Scale
VP_TONEMAPPING_PRESCALE
Parameter: Post-Scale
VP_TONEMAPPING_POSTSCALE
Parameter: Burn
VP_TONEMAPPING_BURN