scripting "system preferences" "language & text"

Question

I need to change, using applescript, the listbox "region", in the system preferences|language & text section. I can't access this listbox - see code below.

tell application "System Preferences"
    activate
    get the name of every pane of application "System Preferences"
    set the current pane to pane id "com.apple.Localization"
    get the name of every anchor of pane id "com.apple.Localization"
    reveal anchor "Formats" of pane id "com.apple.Localization"
end tell