With my ball pythons too, I make sure to hold the rodent by the scruff, so it's not dangling head down, and don't bump them with it. Warming it is a great suggestion, but don't microwave it!! Trust me. Not good. A heat lamp, or warm water, or even putting it into an empty bin. If she won't take it off tongs leave it with the lights off to see if she'll eat it after poking around it a while.
Don't get discouraged either, it might take time, but it's always worth getting them onto f/t. I'm starting to work with mine, since with my schedule, I have less time to clean up after rats. If I'm going to have to buy my rats, buying frozen ones from someplace like RodentPro is much cheaper than buying live rats locally. (Even if I have a source for $1 each)
Good luck!
*Disclaimer* These suggestions come from my direct experiance with my own reptiles, and in no way constitutes a legal advising of husbandry. The poster has no vetrenary license and does not practice for any amount of funding, but rather imparts advice from her own feeble-minded achives of knowledge. All advice taken is measured by weight not volumne and some settling may have occured during shipping.
Wolfy