The owner's manual will tell you what to do. My new Honda's manual says to avoid 'sudden' and 'full throttle acceleration' for the first 600 miles.
Yeah, but with a 78 HP motor, it's kinda hard to avoid full throttle and not get run over, no? Obviously, not being a road hazard takes priority over "perfect" break in! However, I would not hesitate to get in the "truck lane" and go slowly uphill, if it keeps you from a downshift. (Usually, you can tell when giving it more throttle will result in a downshift, or at least I can.) I know people who will FLOOR a car to maintain 75 on the upgrade, and to heck with downshifting into second! To me that just seems unnecessary.
One specific thing I’ve heard as a recommendation, is to lock out overdrive, then accelerate from HWY cruising speed to about +10 above, then coast back down to cruise, repeating this cycle a half-dozen times or so. This is, I’m told, to properly seat the rings–the manifold vacuum helps draw oil up over the rings, and the acceleration helps them conform to the cylinder walls. Don’t know how much difference it makes, but it at least gives you the illusion of “doing something” to help out…passes the time, if nothing else, and probably doesn’t do any harm.