best FE technique for steep highway hills?

My little red Insight is up to around 450 miles on the clock now. Lmpg is steadily climbing from the 18.7 it had when picked up .. it's around 48 now I think.

The car unfortunately didn't come with a manual (the dealership misplaced it while the car was on display at the recent New England International Auto Show) and I haven't yet gotten one, so please help me out with something:

This weekend I'm taking a highway trip out of state. The ride will involve some pretty serious up- and downhill grades .. this is New England! From playing on the local roads, I've learned how to rollercoaster the car through the occasional dip and climb. For prolonged steep hills, however, I haven't yet figured out how to keep the car out of assist.

How high do the rpm's need to be (probably in 2nd) to keep the assist from coming on when going up a long steep grade? And whatever rpm that is, is it too high for an engine that's still in its break-in period?

Can't wait to get the car up to 5K+ miles so we can put synthetic in the engine. Huh, maybe it's worth doing a _lot_ of driving this year just to get it up there. I can think of lots of excuses to go shopping!