I know this process has changed from 5.0 to 5.1. Proxy.xml is no longer found in /etc/vmware/hostd/proxy.xml. From what I've seen in http://communities.vmware.com/message/2160793 you need to configure the config.xml file in /etc/vmware/rhttpproxy
As the problem shows in that other discussion, the changes don't take hold after a restart.
Has anyone been able to successfully change the management ports in ESXi 5.1?
Thanks,
Chase