Without seeing your project, the answer isn't going to be very helpful:
Bend over really far.
I don't know how or why you would need to do it this way, can't you make arrangements with your neighbor? If you are needing to ask this kind of a question, and knowing what I do about masonry walls and what happens to them when they are built by people who don't know what they are doing, I would recommend you get some quotes from some local masons.
Especially if the wall is going to hold back dirt.