yes you can in any version of eSmith.
Just set it up that the external interface uses a "static IP"
External access mode: dedicated
External interface configuration: static IP
Select static IP address: 10.0.0.1 (or whatever you set your external ethernet card address to be)
Select subnet mask: 255.0.0.0 (or whatever mask that corresponds to the IP address above)
Select gateway IP address: 10.0.0.138 (or whatever you set your router's/ADSL IP address to be)