my friend has a spot right outside her garage door that she dug up the grass (about 2 ft x 2 ft) and put down cedar chips ......she trained her dog to go pee on the cedar chips. cedar is an odour absorber and she would just replace the chips 2 or 3 times a year. so i guess you would start by taking the dog out on a leash and go straight to the chips and say "go pee" and then eventually it would just be where they go ....