You cant legally, so hes obviously screwed.
You can enthusiastically ask to be caned, but if you then showed those bruises to the police, then whoever did it to you would be arrested and probably charged, as you cannot consent to actual bodily harm.
Its quite a topic in the BDSM community and I dont agree with it, although in this case the woman died, so I think he deserves what he gets, and this was not in a BDSM relationship and even if she did drunkenly ask for it, that would not be considered consent in BDSM nor the law