I recommend you... (or your friend? We don't use poor self-incrimination deflection techniques such as SWIM, my dog, my pony etc) to check out Basic Drug Discussion and Other Drugs to see other people's experiences with IV. It can be dangerous if you don't know what you are doing. Try and avoid it as best you can, because for many people once they try it then they can't go back to other ROAs.
I think you should check out these threads too, good luck. I'll move this thread over to Basic Drug Discussion in hopes that someone can provide you a safe answer. Any queries or questions feel free to PM me.