Use a crate to discourage house soiling, but do NOT scold your dog for not eliminating. How in the world is he supposed to know what he did NOT do?
In general, train the older dog the same way you would a puppy - with frequent trips outdoors, crating and regular feeding. Never punish your dog for an accident! If you do, you run the risk of him making an unintended association between you and bad feelings! He is likely to eliminate out of your sight following punishment.
If you have a dog that should be housebroken but isn't, the first thing I would probably recommend is a trip to the vet to rule out medical causes. After getting a clean bill of health, you can start to work on the house training.