IPV4 and IPV6 on the same virtual server.

Your VS is IPv4 or IPv6 but not both at the same time. Why do you need this? I think your only option is have separate VS.

Daniel is correct. You can use two virtual servers, one with an IPv4 address and another with an IPv6 address. They can both load balance to the same pool of servers. The BIG-IP will act as a gateway between the IPv6 traffic on the client-side and the IPv4 traffic on the server side.