Hi Alan,
Before going down that route, just do a check and make sure you have supported hardware in terms of that NAS...
http://seer.entsupport.symantec.com/docs/237737.htm - NAS Appliance Compatibility with BEWS 10.x
http://seer.entsupport.symantec.com/docs/247059.htm --> How to determine if your NAS is compatible with BEWS
Once done, you can configure that NAS as a backup-to-disk target for BEWS.
Laters!