You really ought to consider switching ROA. I know that's probably not want you want to hear, being an IV drug user myself, I understand that once you turn to the needle, it's almost inconceivable to go back. But if your out of all your veins in your arms and hands, you should consider plugging instead. It's the only other ROA that has almost as fast of an onset as IV, and usually a good BA.
You especially dont want to be messing around with hard to hit veins when shooting coke. It's hard to tell when you miss a shot of cocaine, as it numbs the injection site almost immediately, even before you deliver the shot. I don't want to condone smoking freebase, but if you want a similar rush, you might consider doing that instead. Missed shots of coke can be really nasty, especially with the horrible cutting agents they're using today.
Also, a missed shit in the foot or legs is more dangerous, as the circulation is slower down there, so you're more prone to infection and abscess. Check out a diagram of the veinous system in the arms. I imagine you still have one or two left that are usable, if you are definately going to shoot.