Here is a sample VSS configuration for 2x Cat6500 with Supervisor 720.
VSS domain config:
switch virtual domain 10
switch 1
switch 1 priority 110
switch 2 priority 100
exit
Create a Port-Channel "mode on" type between two Supervsor:
interface port-channel 1
description VSL Link
switch virtual link 1
no sh
interface range T5/4 -5
channel-group 1 mode on
no shutdown
Commiting following command will save the configuration on both switches and reboot them.
switch convert mode virtual
After the reboot, we need additionally apply this command:
switch accept mode virtual
Now, lets verify the VSS status:
show switch virtual
show switch virtual link
show switch virtual role
Remember to apply this also:
mac-address-table synchronize
redundancy
mode sso
exit
Hope it helps