I'd put one heat pack in with her at a time. Either put it in a deli cup with holes, (like you'd have for a hatchling) or wrap it in newspaper. I don't think the ones you get from a store last as long as the ones we use for shipping, so you'll have to check it regularly, or put a probed thermometer on it.
I'd wrap her viv with towels/blankets, put the heat pack near where she is digesting, in her viv, and cover the top of the viv with towels to keep the heat in. Really, though, you can't heat the whole thing, you just need to keep her warm right where she is.