I worked on this a bit today
it will first read all the fields you have in your media center that includes all the user created ones.
the plug-in will put this list in a check box listing and all you need to do is check a box for that field to be exported.
it has a configurable export file names like
[Artist] - [Name] - [CurrentField].txt
if you select "Batch Export" it will export all fields you have checked in the list as text files, to the media file folder or to a folder you select.
like (Next To File)
C:\My Music\N\NSYNC\NSYNC - Celebrity - GirlFriend.mp3
C:\My Music\N\NSYNC\NSYNC - GIRLFRIEND - Lyrics.TXT
Or
C:\My Music\N\NSYNC\NSYNC - GIRLFRIEND - Lyrics.MP3
C:\My Saved Data Files\NSYNC - GIRLFRIEND - Lyrics.TXT
it also works in reverse where you can "Batch Import" the fields from text files.
It also Has A Manual Mode Where you can select a file and, select a field from the list, this makes this field the current field and then you can press "manual import" or "manual export".