I've been playing with dillies for almost 2 months now, and done everything you can do with them except for IV (like many, that is where I draw my own personal line).
I got them for back pain, and naturally I started off by taking them orally. That way, they really have pretty much no affect at all. Total waste.
Snorting works MUCH better, but the buzz is over pretty quickly (less than an hour, I'd say).
Plugging DEFINITLEY had the best result (there are threads on it, but basically you crush up and dissolve the pills in some water, suck it up with a large, needle-less syringe, plug it way up your butt and fire. Lay there for 15 mins or so (on your side they say is the best).
The high is VERY nice and lasts a while.
At the moment, my tolerance is pretty high so until I can lay off them for a while, no matter what I do the high is pretty minimal.
I've also read conflicting things about hydromorphone's bioavailability, but plugging absolutely gave the best results. For me, anyway.