- Open Script Editor (in Applications » Utilities), and paste the code below into a new script:
- Save your script as Tag Track (or whatever you want to call it) in ~/Library » Application Support » Quicksilver » Actions.
- Restart Quicksilver.
- While iTunes is playing, invoke Quicksilver, hit the period key, to go into text mode. Now type your tags separated by spaces, and choose Tag Track from the actions in the next pane. (Or you can do Tag Track in the first pane...).
[robg adds: I haven't tested this one.]

