From MEPIS Documentation Wiki
Cable connections are routinely similar to ethernet in that you should only have to plug your cable modem directly to the NIC (Network Interface Card) in your PC. Most cable connections send DHCP information for automagic configuration of your PC. It is highly recommended that you have a firewall like Guarddog or Firestarter running if you are connecting directly to the Internet with your PC!!!
If you are running a standalone/external firewall, most of which will run DHCP by default, simply connect to the router/hub/switch and your machine should autoconfigure via DHCP.