Apple - How can I rename a song in iTunes with a keyboard shortcut?
fn + return works while navigating with the up and down keys. Edit the song, then press return again to submit changes.
For the other columns just press tab to reach the desired column.
Press ↑ Up or ↓ Down to go to the track in iTunes.
Press ⌘ cmd + ↩ return.
The track name will now highlight and become ready to edit
Enter the text of the title.
Press ↩ return to commit the renaming of the track.
I made a page of this (with pictures) at: http://sites.google.com/site/chrislent/home/rename-a-track-in-itunes-from-the-keyboard
See Apple KB Article PH12110 for an exhaustive list of keyboard shortcuts.