Yep, all you need to do is
Mac# touch .com.apple.timemachine.supported
Go to the terminal...
Connect to your NAS.
create a file named ".com.apple.timemachine.supported" on your NAS.
The simplest way is to use "touch .com.apple.timemachine.supported".
Then, you can go to your TimeMachine menu and use it as your backup drive.