Of the twin moms I have met, all "had" to deliver in the OR. Most ended up with c-births.
However, I have a friend that had twins recently and ended up w/a footling breech presenting in labor. Her OB said she would have been able to go vaginal with a regular breech presenting, just not footling breech. And she also said 2nd babe could be in ANY position, they can and will attempt to turn if need be after first babe is born. This was in St. Vincent's hospital, just outside Portland. I was surprised, as I hadn't heard very good things as far as natural birth goes at that hospital, but who knows, I guess it varies by doctor. If she is only comfortable in a hospital, have you tried the teaching hospital, OHSU? I have heard ok things about them for twins.
And I highly second finding a midwife. We are blessed with many wonderful midwives in the Portland area, I am sure Pam would be a great help if you spoke with her. I wouldn't step foot in a hospital with twins, unless it was an emergency, but that's me!
Hope it works out for your daughter, keep us posted!