You don't need a real incubator, what's more important is keeping your temperature & humidity steady. If you can provide a condition for your eggs where the incubation temperature stays within a few degrees, and humidity stays around 80%, then you should be fine.
So however you think you want to do it, just make sure to run extensive tests before putting an actual egg in it. Run it for days & weeks to make sure you can get the temperature & humidity readings to see how well it'll work. You're looking at incubating for 30-35 days for males at 89 degrees, or 55-65 days for females at 81/82 degrees.