I have two geckos and my cats try to attack them and I need to teach them not to attack them because I want to get an iguana and I want to be able to let him or her roam the house without being killed.
Which came first, the cats or the reptiles? My cats love to chase anything that moves which unfortunately includes lizards. If I were to get a gecko or iguana as a pet today, I'll probably have to keep it safe in a terrarium, in a place off limits to the kitties at home.
I hope other more experienced members can help you.
The cats' instincts are to go after prey, so you'll probably have to keep them separated. My sister has dogs, cats and iguanas. She only lets the iguanas roam the house after they're big (over 2 ft.), and the dogs and cats give them a wide berth, because iguanas can give a nasty bite and also a good lashing with their tails.
I agree about the prey drive. There is only so much we can do to curb the behavior that goes with prey drive. When we play with our kitties using interactive toys we are actually giving them an outlet for their prey drive. I would say that you need to keep them separated until the iguana is big enough that your kitty will leave him alone. Of course if your kitty is the type that will go after him even when he is big enough to defend himself then you will still need to keep them separate for your kitties protection.