I can do it consistently no problem. It just takes a bit of practice to learn the exact way to do it.
First and most important, you have to be practically hugging the wall you want to walk on. If your character isn't touching it, it wont work.
So, while running along the wall and hugging it, you just keep moving forward and press jump and the appropriate strafe button and voila.
If you're not moving forward, you'll just do a wall flip.
In either cases you have to be RIGHT next to the wall though. Remember that.