Using python, it’s easy to get data from IMDb into your iTunes database.
You’ll need a few tools to get this working. appscript, py-IMDb and CocoaDialog. Install each of these, and for the latter, note where you store it. I’m not going to go through the code, as it is fairly well commented. If you can’t get it to work, leave a comment and I’ll see if I can help.
Note that you will need to save the file above, and rename it so it has a .py extension.