Dxm and alcohol

I know the synergy is probably not great but I wanna try it. I will throw up 100%, question is how much alcohol and dxm maximum to avoid liver failure? I'll have a mostly sober sitter (only doing weed) so I'm not as worried about vomit aspiration or over sedation, infact over sedation is the goal. Neither is a strong enough respiratory depressant to be an issue iirc. Thoughts?