Can it be Ported to Spartan 6?
There are no plans to port this app note to Spartan-6. The Spartan-6 block is not capable of interfacing directly with another Spartan-6 block so the techniques in this app note cannot be applied.
To connect two Spartan-6 devices together, you would have to do a peer-to-peer type setup through a switch.
You could also connect a Virtex-6 device using it's block in root port mode to the Spartan-6 endpoint.