I'm not sure it's best to try to maintain a high cadence going up a hill. 5% grades kill me too over anything more than very short distances; I'm still bad at hills. It would make more sense to me to slow your cadence and either stay in the saddle or stand up (or alternate between sitting and standing) as you're ascending. I could be wrong, but it helps me.

How does the old saying go? "It doesn't get easier, you just go faster" or something like that...