How could I do this?

If I understood correctly, in other words he is the owner and you are the tenant. You are paying rent to the bank i.e his mortagage payments. I dont know what made you to do this, I think the only way is he has to sell the home to you. Your name is not in any of his records. At the time of purchase you would have added your name with even 1% down, then it would be easy to take out his name and convert into your name. Good luck my friend.