For any of you who don't want to survive a heroin overdose, you need to potentiate it with another CNS depressant (benzos, non-benzo hypnotics- ambien[zolpidem])
It seems most heroin overdoses occur with valium, xanax mixed with heroin.
To succeed, I would do it "slowly" since the human body tends to violently reject any substances detected as toxins being consumed in a large amount;
In other words, I would taken 10-20 xanax slowly over a few hours, then snort the heroin (slowly to avoid puking), then take some anti-emetics like domperidone to prevent nausea and vomiting.
Alternatively, if you can't get many benzos due to faggy doctors (lol), I would get other CNS depressants (with the exception of alcohol since you can aspirate), like antipsychotics, antihistamines and zolpidem or zolpiclone.