A box isn't necessary, although you can use a small kitty litter-type box if you want. You can let the female incubate the eggs herself. This way you won't have to worry about maintaining the proper temps and humidity as she will do that on her own, however she will not be eating for the additional two months it will take to incubate the eggs. This is one of the main reason why people prefer to place the eggs in an incubator.

The temps should remain the same (low 80s to low 90s), but you should bump the humidity up a bit.