In the meantime restrict him to less space until he gets the idea. Like a small kennel . He will learn if he is not allowed to have alot of area to move around in. This is not mean it is teaching him there is a place to sleep and lay down and there is a place and time to relieve himself. I have housebroken many dogs over the years and the trick is they generally won't go where they have to lay down.
But make sure he gets to go out and get some exercise! I know you don't want him but this is damage control and it is tempory.