The key thing to remember is that you can't
make them learn it. It really has to be something they want to do. If you try to force the issue, you're really just pi$$ing up a rope. (pun intended.
)
The bottom line is this. All they've ever known is dumping or whizzing in their diapers. Mom or Dad will deal with the mess...no big deal. It's gotten them through this far in life...
Once they get motivated about it and really, really want to start, they'll pick it up extremely quickly. Your job is to figure out how to motivate him. I'd highly recommend steering clear of the "ridiculing" method. Chances are, that won't work, and will only drive them further back to the diaper.
Most of all, just know that it will happen. He'll learn it when he's ready.
Randy