The other possibility aside from a step infusion, is to do a decoction. After douging in at the acid/protein rest, remove about 1/3 of the thick portion of the mash (mostly grain, a bit of liquid) to a separate pot, and slowly heat it to the saccharification temperature, stirring constantly so as not to get any scorching on the bottom. Leave it at that temp for 15 minutes, then continue heating it to a boil, again stirring the whole time. Once you get to a boil, recombine it with the mash to raise the grain bed temp.
I have to say you might have to do a little trickery there with the calculations and amount to decoct, because going from 112 to 152 is kind of a big step for a decoction...it is usually more like 25-30 degrees so you might need a bit more of the mash. If you use brewing software like beersmith it can help you get to the right temps easier.
You could also step mash like that with the whole mash...just be sure to stir constantly at relatively low heat, and especially make sure you don't get grains stuck on the bottom. If you feel like grains are sticking, immediately remove from heat and maybe add a bit of water to help it get unstuck.