if i were on death row and was able to choose the way i would die, i would choose the guillotine, Co2 chamber or lethal injection.
guillotine is fast and for the most part, painless. as mentioned before, the head can still remain concious for a while, which is scary. i could see how it's hard to cut the head off of a baby chick, but this is the most common method. have the hubby/boyfriend/brother/father do it. you don't have to be there and for some reason hubbys/boyfriends/brothers/fathers don't seem to have too much of a problem compared to us ladies.
now for C02 chambers. Co2 chamers allow a person to have the comfort of things like TV, music, a comfy chair. and you just fall asleep and die. it's just like normal breathing, as Co2 has no smell or taste. the reason Co2 that comes from cars stink so bad is because of the other chemicals involved. you can make a Co2 chamber for small chicks by using clear sealable container for the chick, and a larger sealable container for the Co2 producing chemicals (baking soda & vinegar) use a tube or hose to connect the two at the lids. put your chick in the small clear container. you can also put a heating pad, soft bedding, a favorite toy or just about anything to comfort her. close the container, be sure there are small vent holes in it to let the oxygen out so there is not a vas amount of air pressure when the Co2 is produced. then go to the larger one, put in the baking soda, then the vinegar (use your own judgment on how much. this container should be fairly large) and quickly close it. you can even hold the chick to comfort her if you use a cloth or towel to block the top of the container she is in.
now the one i would more likely prefer. i think we all know about lethal injection. you can have her taken to a vet and she will pass on peacefully with no pain.