Hi,
yes it should be possible. You must mark all traffic in the vlan 3 (with dscp 10 for example) and drop the exceeded traffic through a policy map:queue.
Switch(config)# policy-map flow1t
Switch(config-pmap)# class ipclass1
Switch(config-pmap-c)# police 10000000 8192 exceed-action dscp 10
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# switchport mode access
Switch(config-if)# service-policy input flow1t
The policy works only incoming, but when you enable it on both sites it should works.
The link will help you with the configuration:
http://www.cisco.com/en/US/products/hw/switches/ps628/products_configuration_guide_chapter09186a00802c31e8.html#wp1083017
Regards
Peter