I'll admit this isn't a feature I use often, but I just went down to the car to give it a try.
So obviously you have to be connected to USB, and your smartphone setup should have iphone/ipod set as the device on the NEX, and the connection method should be set to USB.
You also have a setting in the NEX settings screen that indicates which USB port the iTunes tags are sent to. That defaults to USB1, though you can change it to USB2 if that is where you plug your iPod in.
If you have it setup and connected you'll see the little tag icon toward the lower right of the screen on the NEX when a song is playing and tag info is retrieved. Tap the artist or song name, and you'll get a little option window that asks what you want to do with it - memo or tag - hit tag.
When you go back to iTunes and sync you should see the tagged playlist show up in your iTunes library - not the device. From there you can click View to find that song in the store.
For reference, I tried with an iPhone 5s on a 8000nex. My iTunes version is 11.3.1