Parse the selected iTunes tracks' Song Names such that the same first Item text in "First Item - Second Item - Third Item" is removed and copied to another user-selected tag in each selected track (Album, Artist, Composer, Genre, Grouping, or Comments), leaving "Second Item - Third Item" in the Song Name. Run the script again to similarly remove and copy "Second Item" to another tag, and so on. Read Me explains more, and how to customize for different separator characters. Screenshot speaks volumes.
(Note: In order to launch this PowerPC-era script on an Intel machine, it must first be opened and then saved using AppleScript Editor, which is located in your /Applications/Utilities/ folder. More information is here.)
Applet assists with swapping, copying, appending data between track tags
Perform various tasks on a selection of playlists; rename, delete, duplicate, merge, more
Batch set new Last Played/Last Skipped of selected tracks
Move selected playlists to a new or existing folder
Perform search-and-replace on text in your choice of tags
Restore each selected track's artwork from an image file stored in its Album folder