yeah.. unfortunately it's really hard to taper with short acting opiates like heroin, especially due to the fact that they are so fiendish. For right now, you might want to try and limit the ammount of dope you do in a day. I'm not sure what your habit is, but if you're like me, you're probably using more than is actually necessairy to stay well.
For instance, when I was heavy into heroin, I would use 1 to 1.5 bundles of IV dope a day, doing shots around the clock. Needless to say, I could have definately gotten by with probably half a bundle, but I wanted to get high as well. If you're an I.V drug user, I imagine you're probably doing a couple shots in a day. I would first try and limit the ammounts of shots you do. If you're using four, try and go down to three, than two.
The problem is that it's almost unheard of for someone to taper off of heroin. It happens of course, but the ammount of will power it would take, would be far more than impressive. If you can't get suboxone or methadone, try using Immodium (loperamide HCL). Another useful drug is Gabapentin, which will take care of many withdrawal symptoms and make kicking way easier.