Pressing the control key with AppleScript
If you need to do something and hold it down, try something like this:

                tell application "System Events"
                    tell process "Photoshop"
                        option key down
                    end tell
                end tell
                DO OTHER STUFF HERE
                tell application "System Events"
                    tell process "Photoshop"
                        option key up
                    end tell
                end tell