True, you do need a lot of discipline to teach yourself. However, I did say that "IF he is motivated" he could pick up a fairly good working knowledge of the language in 2 years. I think that's an entirely possible scenario. I don't think you have to be the EPITOME of disciplined, just motivated.
Kanji aren't much harder than any other aspect of the language, if you get over the fear of them. Using a system like Heiseg's would speed up your progress, IMO to the point where 2 years self-study would give you a solid grounding in a lot of the jouyou kanji.