Try connecting it to another Windows system first and see if you then have access to the data. One brute force method of access would involve a system with Linux running, but you would need a PC with Windows or Linux to try both. From the mac computer itself, I have doubts that there is a way around this. I find Apple products frustrating when it comes to certain things before they give you enough access to get by but not enough to feel like an admin that can take control of stuff like data permissions.