Importing password file into local vault

My computer recently became unbootable and eventually required a clean install of Windows 7.  However, I have a mirror drive (also unbootable) with data intact.  Also, I have a good backup of the computer pre-unbootability.

I have reinstalled NIS, and I know the old password file for the vault is around somewhere.  But how do I find it and then import it?

Many thanks for any assistance!