This is pretty much a rhetorical question, but indulge me if you don't mind

A Localisation fella I work with asked me if it's possible to change the browser language settings in I.E. using Javascript.

I suspect that the answer is an emphatic "No!" as if it were the case then it would suggest that you would be able to change other things in the options panel which compromise security such as Security Level.

I'm right, aren't I?