Changing language settings in Spell Checker using scripts

Is there anyway to change the current language in use by the Apple Spell checker service using scripts? I found the file
but this doesn’t seem to be scriptable. Do I need to look deeper?

I often write email in 3 different languages and would like to be able to switch between languages using only the keyboard. Right now I have to bring up the spelling panel, and use the mouse on the pop-menu, or a complicated set of keyboard commands, to switch from English to Spanish.

Hi I have exactly the same problem, I think you should take a look here
I have just found it, it looks very promising.
I would take StefanK’s advice from the thread

works great