DLSS 4.5 with spectral data for arbitrary wavelength sampling, or only with Color3?

I saw the example code by Dylan Lacewell for DLSS 4.5 (OptixSubd), which appeared to make use of a Float3 color assignment for the radiance. Is it possible to also use DLSS 4.5 for an arbitrary wavelength sampling as well, or does it need to be downsampled to a maximum of 3 channels prior to use with DLSS 4.5?