What kind of a tolerance do you have? If none or little you might just want to snort 2-4mg instead of the whole 8mg. While I don't think the whole 8 would be very dangerous on its own ( no other drugs involved ), it could potentially be enough to have someone opiate naive become very uncomfortable ( puking , clammy, sweating, cant see straight etc ).
And yes besides IV the next best thing is probably intranasal.... perhaps plugging but I don't know very much about that MOA.....do a google on hydromorphone rectal and look around bluelight for more info on it if you decide to go that way.