Static IP setup

I need some help with setting up a firewall with a real ip address. We have qwest Adsl service and I want to tranfer over the firewall to an appliance instead of using the router. My question is setting of the gateway and netmask on the appliance. The ISP protocol is PPPoA. Do I need to worry about these or do I only need to set the DNS servers for it to work? Will it need to be pointed to the router in some way? The firewall appliance is a linksys RV0041.