I think you should look outside the coaching literature and have a look at what have been done in CBT where the results are quite good. This recent review is a good start.
Rozental, A. & Carlbring, P. (2014). Understanding and Treating Procrastination: A Review of a Common Self-Regulatory Failure. Psychology, 5, 1488-1502. doi: 10.4236/psych.2014.513160.