Deploy vCenter Server 6.5 as normal, except ensure that you register vCenter Server with the Load Balanced FQDN for the PSC 6.5 HA instance.
The same is true for additional solutions that would register with the PSC (SRM, NSX, vSphere Replication, etc)
Deploy vCenter Server 6.5
If vCenter Server 6.5 has already been deployed to one of the PSCs then simply run the following command to repoint to the PSC HA VIP Address
/usr/lib/vmware-vmafd/bin/vmafd-cli set-dc-name --server-name localhost --dc-name psc-ha-vip.domain.com
Restart the vCenter Server services
service-control --stop --all service-control --start --all
If other solutions like SRM, VRA, NSX, were already deployed against a PSC, they will need to be re-registered with the PSC HA VIP.