I suspect there is likely a way with some combination of drugs? But as for how reliable it is I doubt it will be very effective.
A method I am more familiar with would be the bleed-out bathtub method, basically someone will cut open both their wrists in a bathtub of warm water. The warm water is soothing and help keeping them calm, on top of that they won't feel cold from bleeding out until much later since the warm water helps prevent that, as well as making it less likely for their blood to clot and stop the bleeding.
That being said this method is also highly dubious at best, since a person likely to survive for a multitude of reasons such as SI, not cutting deep enough, or even from their blood clotting in the wounds as it isn't impossible for that to happen.