Couldn't you just drain some of the wort off at the 122 point and heat it to roughly 155 and add it back into the mash to raise the temp and use less water additons?
I have heard of this and gave it some thought, but the details worry me. You'd have to heat the wort to well over 155 to get the grain bed to the desired temperature. I don't know how to calculate the right number and am not sure if it would get to a temperature that might effect enzymes and flavor. BeerSmith gives me all the step temperatures for the method I plan to use.