Most of the time, putting it as close to the broiler as possible is the best way of heating it. In your oven, I'm willing to bet the broiler shuts off prior to heating to proper temperature. I usually prop the door slightly open with an oven mitt to allow heat to escape, which keeps the broiler on to continue to heat the stone up. Depending on how close you can get the stones, you should be able to get it up into the high 600s or low 700s with your oven.
Depending on how close the stone is to the broiler, you may have to lower the stone 1 level prior to baking. What I typically do is use the hot stones and the broiler to cook the pie. Once the top is done, I turn the broiler off and depending on how hot you got those stones, the bottom may or may not be done. Heh, one thing is, you never want the pie too close too the broiler. I've had it rise a lot during baking and next thing you know, the dough has caught fire cuz its in the flame.