Add amazon ELB's behind a F5 Loadbalancer

Thanks for the response. I have an F5 Loadbalancer configured on Amazon EC2. I am trying to configure the pools to resolve to an ELB CNAME. For some reason when i give the came address of the ELB in the pool hostname, its resolving to a single ip of ELB . As you know the ELP ip's are dynamic and changes as ELB Scales UP/Down. Also there are 3 IP's for ELB if its distributed to multiple AZ's. How can i configure my pool to resolve to all 3 IP's and dynamically update when the ip changes.