I didn't see this ticket and have also started work on this. My progress (and it is still in progress) is here:
(I have still to add tests and remove some code duplication with other amazon drivers).
There are some interface violations I need help with:
1. balance_attach_member is not supported by aws, only balance_attach_compute_node
2. A backend cannot be given a particular port. Rather the backend port has to be passed to the LoadBalancer when it is created at the same time as the front end port. To clarify, on other providers you might have a LB on port 80 that directs traffic to 8081 on host a and 9081 on host b. On ELB, you have to pass the 8081 to the load balancer when you create it and you can then only use 8081.