I just did this with a 3yr old ES, he came from a Field Trialer who claimed he had been in the house at one time, but not in a long time. I wasn't sure how true that was because he knew I wanted a house broken dog if possible. I will say it was fairly easy, as an adult dog should be more calm and will lay down more during idol time. I just watched him like a hawk, and if he showed any signs of sniffing I let him outside, I never left him out in the house alone either in his kennel, or locked in the kitchen {no carpet]. He had very few accidents, I also made sure he had lots of exercise, a run almost everyday. I did have a start as the owner knowing I wanted him in the house brought him in his house during the time before I could pick him up, I think that was 4-5 days. One thing this boy liked to do was lift his leg on people he first met, my daughter, the vets assistant, but after catching him a couple of times he stopped, but when he meets someone new I still keep a close eye on his leg.