Hi Joanna,
Can you explain more about your requirement?.
When you say the servers requires multicast. Are they going to be receivers or Mcast source?. who will be audience for this multicast traffic?.
If your requirement is in a way, only these 6 servers will be communicating among themselves using multicast, I guess you can achieve it with current 6509 by having them in separate VLANs.
Regards,
Nagendra