Personally, I'd let him go.
In downtown Baghdad
He has shown a total disregard for justice all of his life, he doesn't recognise the court, he doesn't recognise the ruling.
He has killed thousands of Iraqi people, if he doesn't recognise the court, the court should let him go.
Hanging is too good for him anyway, he's sentenced hundreds of people to death by stoning, give him a taste of his own medicine.
This is going to be a minefield whatever is done, whatever to do to him is going to cause unrest, the only way to prevent a full blown civil war as a result of this is to act fast.
Whatever they are going to do to him, they need to decide and do it before the Baathists have a chance to prepare.