I would recommend you get a card reader. This would make the SD card act like a hard drive. Then run Disk Warrior.
Thanks. Is there any specific card reader you recommend?
Any of the generic USB2 or Firewire readers should work. However, I'm not so sure about my recommendation now. After thinking about it a while, I'm not sure DiscWarrior is going to know what to do with a PC formatted disc. It's designed for Mac OS partitions.
Wayne