This has helped me:
During thier run-up, most people focus on the first place they are going to plant thier foot on the wall. This is good technique, but if you're stutter-stepping, it may be because you are getting worked up about that first kick. Instead, try to focus on the place where you will plant your foot to leap off the ground. When you reach that point, immediately shift your focus to the wall again.
Once you get that down, focus on where the foot is going to go immediately prior to the lift-off one. When you get there, shift your focus to the next step, etc.
If I find myself getting worked up about a wall-run, I'll use this technique and typicly plot out three or four steps from the wall. Hope that helps!
Oh and also, many of the other methods discussed above, such as practicing large leaping bounds, are very helpful as well.