A Script to Make Shortcuts
Here's a script I've been working on that lets you set shortcuts to your iTunes Scripts. Warning: advanced scripting ahead!
The method of adding keyboard shortcuts to the scripts in your iTunes Script menu is described here. But I was playing around with iTunes' .plist file and some Terminal commands and was able to put together a script that allows Command, Shift, Option, and Control plus a letter key to be assigned.
Go to download the script.
First, some basics
This script uses a shell script to access iTunes' .plist file and assign a series of keys to the name of the script. The name of this file is "com.apple.iTunes.plist" and it is located in Library > Preferences. If you double-click on it in the Finder, it will open in the Property List Editor application. You can also open it from TextEdit to view the unformatted raw data.
The section of the .plist file that contains the shortcut info will be listed under the "NSUserKeyEquivalents" key. This contains information for user-created shortcut keys that are assigned to menu commands:

Three of my scripts have been assigned shortcuts, according to iTunes' .plist file.
Conveniently, the names of scripts in iTunes' Script menu are interpretted as menu commands.
In the assignments above, each script name is associated with a keyboard key combination. The key combinations are made up of two or more of the four special keyboard keys, identified with abbreviations:
- Command key - "@"
- Option key - "~"
- Shift key - "$"
- Control key - "^"
Thus, above, I am using Control-Command-X for "Pretend We Played This", Command-Option-C for "Quick Convert", and Control-Command-L for "View Library".
(F keys are also configurable, but I haven't included them in the script. Future release.)
You can read and write to the .plist file using shell commands in Terminal, foregoing the need for editing with Property List Editor or TextEdit. To read the current settings for NSUserKeyEquivalents, enter in Terminal:
defaults read com.apple.iTunes NSUserKeyEquivalents
The output is a list of menu items, uh, I mean Script menu items and the shortcut keys assigned to them.

Reading the defaults in iTunes' .plist file in Terminal.
This is the command string to assign a shortcut key combination to a script as you might enter it in Terminal:
defaults write com.apple.iTunes NSUserKeyEquivalents -dict-add "Some Script Name" "@^L"
The command above would attach the shortcut sequence Command-Control-L to a script; obviously "Some Script Name" would be the name of a script.
Notice that the last parameter of the command uses two of the four character abbreviations for Command and Control. The shortcut characters have to be entered in specific order. That is, if you use Command, it must be first; if you use Option then it must be next; Shift must follow either of those, and Command must be last. The key that follows that sequence can be any lowercase key, although it has to be entered in caps.
The shell command above can be run via AppleScript using the do shell script command:
do shell script "defaults write com.apple.iTunes NSUserKeyEquivalents -dict-add \"Google Lyric Search\" \"@^G\""
iTunes must be restarted before it will recognize any shortcuts you create this way. The script will allow you to do a series of shortcut assignments, if you wish, before quitting and restarting iTunes for you.
Get the script
Go to download the script.