[clivehawkins]

It certainly is an interesting idea. However, if I've understood correctly, I don't think it's possible - at least not from my point of view. I'm English and so teach British English, not because I think it's 'better' than other forms but because it's the only one I know. In order to not favour one over the other we'd all need to be 'expert' in all the other varieties (US, AUS, CAN, etc).
One thing I DO try though is to use examples \ set contexts from all over the world, not just pulling out stuff solely from The UK.

Anyone else?