I don't know what she's using, but I can tell you what I have used in the past.
There are a few companies that make electric heaters for diving- mostly scuba. I had one with a pad to go in the small of my back and ran off of a battery pack. This would warm up the water by my spine and every time I would move it would push warm water around through the rest of my suit.
I used it a few times with my wetsuit, but I had purchased it to use with my drysuit. It plugged in and heated up part of my underwear. Now, there are better systems, that plug into a full set of electric underwear, and run off of a battery pack. There are some rebreather divers that I know who are pulling 2+ hour run-times, to 320', in 40 degree water who are using them along with thinsulate and argon. They were doing some deep survey work and would stash extra batteries by their stage bottles in case of failure on the way up.
My system was made by a, now defunct, company called Reptative Diver. DUI is now making some systems, and there are others, whom I can't remember, as well. A quick search on the internet for 'electric drysuit heaters' should help you out.
For ice divng we keep coolers, and jugs, full of hot water around to pour into our suits as the day goes on- this would be the cheap way to do it.
Another, sometimes oily, way to do this, that I have seen some divers do, is to attach a hose to a boats hot water exhaust port, part of the engine cooling system, and run it down your suit.
Jon