From Laine D. Lee:
Double-click the Applescript application file to have aliases for all your System Preference panes put into a folder in ~/Documents called prefpane aliases. When you drag this folder to your Dock, you can control-click its icon in the Dock to launch an individual preference pane. You can run the script again if you install something that adds new preference panes, and aliases will be added to the docked folder without your being prompted to do anything else. Alternatively, you could open the script application with the Script Editor and save it in your Scripts folder as a compiled script and run it using the Script Runner or Script Menu. There are a couple of freeware applications that make the individual panes available from the dock, but this Applescript method requires a very slight degree of use of system resources. And using Applescript is fun!!