Ok, I can tell you what I would do but I can't make any guarantees about it. I've had healthy strong chicks hatched this way and I've also had others who were too young/weak to survive. If you were hatching on Halloween, you're in day 22, right? If so, unless the egg was set later (which sometimes happens to broodies in situations where there are other hens), then the chick should be pretty much ready to go.
I'm guessing you don't have an incubator, so if you could set up a small box with a heater or heat lamp (think mini brooder), that will probably work. Carefully chip the shell away at the top/air cell until you are level with the beak. You can do this with a pair of tweezers.
If this is as far along as I think, you should not be able to see working veins in the membrane. Take the tweezers and being extremely careful, tear the membrane back from around the beak, going upward to the top of the air cell. If there is ANY bleeding, stop immediately, put him in an egg carton open end up in the mini brooder, and try later. If there is no bleeding, you should be safe to very slowly remove the membrane from the open top. You have to go slowly because the membrane may be stuck to the chick's body.
Let the chick rest for a while (a couple of hours) in an egg carton, open end up in the mini brooder. After a few hours, try chipping a little more shell away on the side where the chick's head is resting. If you can tear the membrane without bleeding, I would do so just until you can see the foot.
Let the chick rest for a while in the carton like you did above. In an hour or two, you should be able to help the little one pick his head up if he hasn't. After you've done that, just leave him in the warm. When he's ready, he will climb out of the egg, just like he'd zipped it himself.