You don't want them to completely dissolve. You want the oxy, not the binders and other junk...
Its easy. Crush up the pills, throw the powder into some luke warm water, stir it up, throw in some cotton and draw up the water into the barrel through the cotton.
Opiates are highly soluble in water, your going to see a shitload of junk still in the cup/glass/cooker, but thats ok you dont want that shit.
Why would you plug oxy anyways? Ill tell you now before you waste your oxy and shove something up your ass for no logical reason (unless your into that sorta thing). Your better off taking the pills by mouth, or sniff them. Youll get higher by taking them orally, it's tried, tested and true.