This is the script that I use to add some of the metadata to a file after importing it to itunes. Don't know if it will help, but enjoy!
--Before running, create a smart playlist using the "name contains" variable to select the appropriate files. This example presumes you have set a smart folder named "Sample Show Name". It will edit all of the metadata for the shows in this smart playlist as set below. Thanks to allenhuffman on macosxhints.com for the script that I modified to achieve this.
--Sample Script:
set smartPlaylists to (get every user playlist whose smart is true and name contains "Sample Show Name")
repeat with thisPlaylist in smartPlaylists
set allTracks to every track of thisPlaylist
repeat with this_track in allTracks
try
set video kind of this_track to TV show
set show of this_track to "Sample Show Name"
set season number of this_track to "1"
on error
display dialog "Failed to add Metadata"
end try
end repeat
end repeat