Sorry for only responding now.
You change directory to the NSS Volume that you want to the restore the trustees from. In this example it is /media/nss/DATA1/
and type in the metamig command
metamig restore DATA1 -m t -r edir<trustee-bck.txt
You can test to verify that the triustees where restored by using the command rights show, or even better browse to the NSS Volume on a Windows workstation, right click on the folders or home directories, and do spot checks by right click and select properties and OES rights to see if the Trustee rights were restored.
You may also use the man pages for metamig.