Occupational therapy!!! Pronto.
Run out and get a copy of Sensational Kids by Lucy ****** (try your library)
Ideally, you'd get an OT (occupational therapist) who will work with your PT to help the PT understand that this isn't just 'willfulness' but truly sensory. And your OT can work on getting her to wear clothing AND on the hypersensitivity that causes her to be a toe walker in the first place.
Our ds was also hypersensitive to clothing, and after about 3-4 weeks of the brushing protocol the OT showed us, he was a lot, lot better. (As in he no longer needs his shoes 2 sizes too big, and was willing to go barefoot, something he'd never done before.) It took nearly 2 years of OT to resolve some of his motor planning issues, but the clothes sensitivity got better soon.
I second the keens.
The other thing that I'd suggest is a slow desensitization process - the first day, she has to wear them for 3 minutes. The next for 5. The next for 10 and slowly build up the amount of time that she has them on. My suspicion is that once you get to 30-40 minutes, she'll quickly move to being OK for longer periods of time.
Oh, and before you put them on, have her do some 'heavy' motor work - jumping up and down 20 times, stomping her feet really hard. Get some therabands like they use for PT, tie them around her feet so she can move her feet a bit, but has to push against the therabands to make a step (ask the PT about this). That will help calm her nervous system a bit.
Definitely read up on SPDhttp://www.spdfoundation.net/http://www.sensorynanny.com/index.htmlhttp://www.sensory-processing-disorder.com/