I have used my bread machine to knead the challah.

Here's the deal: the challah recipe makes quite a bit of bread (2 large loaves). My bread machine is big enough to let the dough rise for 1 loaf, but not 2. So if I mix up the dough in there (for 2 loaves) I take it out as soon as it's kneaded and let it do the first rise in a large bowl. (Otherwise, the machine will overflow as the dough rises.)

I had also halved the recipe, and then I can let the dough rise in there for the first rise.

As someone else mentioned here, it does take more than 5 cups of flour. That's the starting amount -- you'll have to add more like 8-9 cups I think, total. You can add extras to the bread machine as it's kneading, if it looks too sticky still.

I think I read in the instructions for my bread machine that it can knead up to 10 cups of all-purpose flour, or up to 6 cups of whole wheat flour. At any rate, it does the challah recipe just fine, even though it's quite a bit of dough! :)