Well, internally Beanstalk is Cloudformation stack, which includes: loadbalancer, autoscalling group ans pre configured ami with tomcat.
You have two option how to implement throttling: 1. Setup iptables rules with help of EB configuration files: http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/customize-containers.html 2. Create custom ami. Described:http://blog.jetztgrad.net/2011/02/how-to-customize-an-amazon-elastic-beanstalk-instance/