Most of the favorite marathon plans include hill workouts as an important component. On the coastal plains of Texas, where I'm from, the only "hills" are highway overpasses! Can anyone make recommendations for "hill" workouts on a treadmill -- i.e duration, length of hill segments, incline, and pace? A hill workout on a treadmill, this time of year, would have the added benefit of being inside, out of the heat.

Thanks for any help you can offer.