I'm not sure that using a different altimeter setting is the answer since the necessary correction becomes greater as altitude above the ground station is increased. Aren't approved weather stations altimeter settings already temperature compensated?
However when blended with the ground station pressure and temperature, using DADC output to calculate and display true altitude would be almost as accurate as differential GPS. It's just taking temperature compensated baro VNAV one step further. During extreme temperature ops, ATC might find it necessary to increase separation minima between aircraft, but it's better than the present system. In any case, the problem will likely solve itself eventually when GPS becomes the standard IFR altitude reference for terminal ops. That's a ways down the road though.
So in the meantime, we'd be well advised to use the correction charts when the temperatures start trending towards the extreme.
That's just my take on it though...