have you heard of the 3day potty training method? that does what you'[re talking about (and they have books on it).

the concept is to have the child nappy free totally for three days.
you spend the whole time home, roll up any rugs, spend more time in noncarpetted rooms, put picnic rugs down on the floor, mattress protectors on the sofa.
i didn't use this method so don't know more details, but my friend used the method with both of her kids at two. apparently it can be done at older ages too.

i think part of it is BODY AWARENESS. so that instead of nappy catching/containing his waste, he will get the sensations and see the results, smell the results.

we had potties in various rooms, potette for outings.

best of luck, goggle 3day potty training for more info.