here's what you do. I dunno how similar heroin is to meth, but i know smoking it like this will work. Only thing i don't know is if you'll have to move the puddle around or if it just burns in place.
Get a piece of foil/pizzo or some shit and stick some of it in there. get a straw or cut a pen in half so you can suck through it. Try to make the foil like.. the size of a dollar bill with a fold down the middle of the long part. Put the shit inside of the foil. Hold a lighter under the foil where the shit is... not actually on the motherfucker just enough so the foil gets hot enough to start melting the shit. It should start smoking. suck up the smoke through the straw.. hold it just above the shit. The chunks should be perfect for this. Once it starts melting don't hold the lighter as close.
If it gets all moist and shit and looks like it can move around go ahead and tilt it so it starts running.. tilt it back and forth till you got a nice fat hit. If it gets moist and runny and you dont move it back and forth itll just get burnt. Otherwise whatever itll get burnt anyway.
i don't know if you're supposed to hold the smoke in or not though. Might want to look that up! maybe you could try exhaling almost immediately after you get a fat hit, and if it does nothing, then try holding it in.
also doing drugs like this is more addictive than doing the actual drugs