what i used to do when my younger dog had #2 accidents in the house is this.... 1. get some latex gloves or a baggie... 2. yup you guessed it... pick it up.... 3. take it and the dog out side to the "designated" area... 4. put it down and then let her sniff around a bit (kinda like how you can teach an older cat how to use a litter box)
be sure and praise him big time when he gets the idea..
hope this helps
I read in your other post that you have wee wee pads in the house. Maybe he thinks if he can pee in the house, then it's alright to poop in the house. I think the elimination of the wee wee pads may help.