Yeah I agree with Phreex.....it's something I've done a lot in the past (not with coke though), but it's not something I would ever recommend. The first question that comes to my mind is; why would you want to inject coke alone? I'm guessing you are addicted to cocaine, becuase I don't know any casual users that use coke alone (it's more of a social drug I guess), and if that's the case then, well, drug addicts are known for doing stupid, unsafe things to get high. Lord knows, my reason goes out the window if I'm dopesick. If you do decide to inject alone, just be sure that you start with a very small amount and don't get carried away, or you could end up in a very bad situation.....
Think about it; if you do OD, there is a MUCH higher chance of you dying unless you are able to get to a phone and call 911. This might be difficult if you are having a heart attack 8) Even if you are able to call 911, that means you are going to have EMS and probably the police up at your house, which could very well lead to a bust if you have any drugs around - chances are, if you're OD'ing on IV coke, you're not going to be able to hide your drugs and works, or whatever. If a friend is with you, they can drive you to the hospital, or at least clean up any drugs/paraphenaelia.
There's few things worse than OD'ing on drugs, but one of them is getting busted at the same time 8(
peace
and be safe
CT