Hi
I had a similar situation recently (though the trigger for broody to leave remaining eggs was that two had hatched and she took the chicks away for food). I had one egg pipping in the abandoned nest.
I didn't have an incubator either so I kept the egg warm on a
warm water bottle, kitchen towels moistened with warm water for humidity and an upturned glass bowl as a cover which I kept dunking in hot water to warm up (in hindsight it was probably a bit too warm) I practically stared at the egg for 12 hours until it hatched successfully.

(I have also heard of ladies carrying about to hatch eggs in their bra to keep them warm, as weird as it sounds it seem a good idea to me

I only carefully opened the pipping hole a bit more, just enough to see that the chick inside was breathing. Then I spent some time googling and stumble on this guide
http://www.backyardchickens.com/a/step-by-step-guide-to-assisted-hatching]
- as a result I kept well away from rushing things, which in hindsight was all-important (you may have killed the first chick by getting it out too early).
If you can keep them reasonably warm, and the membranes moist, have the time to keep a close watch, and stay away from rushing things, then you could be in for a good chance I think. Good luck!
