AWS EC2 Load Balancing: point to specific AMI

I'm using the EC2 load balancer. Since I'm implementing my own autoscaling policy, I will not use to auto scaling EC2 service that I imagine is well integrated with the Load Balancer. Basically I will scale out istances all from the same AMI. I notice that the load balancer ask to specify all the instances ids whose workload have to be balanced. My question is: it is possible to instruct the load balancer to automatically distribute the workload among all the instances belonging to a given AMI? In this way every time my scaling system scale out an instance of the given AMI, I don't need to add the new instance to the load balancer configuration. I search about this on google, but I didn't find any useful information. There is maybe something I'm misunderstanding about the load balancer usage? Because to me it seems to be a quite common feature a load balancer should have. Maybe apply balancing over a given AMI would cause some problems I cannot see? Thank you all in advance for the help.