It depends on how steep we are talking here, because eventually if the climb is too steep the laws of physics are going to win. But typically on most climbs you just downshift into an easy gear and spin up the hill. The idea is that you don't want to be standing on the pedals and exerting a lot of force which will break the back tire loose.

Your intuition should pretty much tell you what is too much. Climbing on ice I try and find the lowest gear that is practical to maintain speed and get up the hill.