If you open the (OS X) Script Editor application and choose 'Open Dictionary' from the File menu, you'll (eventually) get a list of all scriptable applications on your disk.
Unfortunately, you'll notice that System Preferences (like most of the apps that come out of Apple!) is NOT scriptable (way to go, Apple!. <sigh> )
However, you can launch Classic easily enough by having your script open a Classic application. This will launch Classic if not already running.
However, the same can't be said about quitting Classic. I expect that 'tell application "Finder" to quit' will kill the OS X Finder. the only other one I can think of is unsafe, and involves killing 'Classic' by pid, assuming you can find it in the ps