How I emulate pressing the Fn key on a Mac OS X keyboard using AppleScript

As a quick source code example, this is how I emulate pressing the Fn key on a Mac OS X keyboard using AppleScript:

tell application "System Events"
    key code 63
    key code 63
end tell

The key code for the Fn key is 63, so all that code does is emulate pressing that key twice. Doing this triggers the Mac speech-to-text facility, which I use in my Sarah application (like Siri for the Mac).