The Backwards Hammer Jump is a method that I found, where Mario cannot gain hyperspeed, but he can climb a wall like in Getting Over It.

Be close to a wall, and turn around so that the wall is behind you. Now jump, and once you can't go any higher, use your hammer and jump again at the same time. Repeat that until you reach the top of the wall, then you can get over it.

Here's an example of BHJ in level 5: