I put the computer screen kind of in sight from the toilet so my son could only watch his favorit movie from there (Cars of course).
We kind of learned (the hard way of course) he wanted to poop around supper time (as all the kids) so before supper we invited him to "watch" Cars while on the toilet.. In 2 days he was trained.. Incredible.. Since then just one accident and that was like 6 months after cause he was playing and was 1 inch too late :(