Then it's just ethernet, unless you need some PPPoE or PPPoA software to make it work. If that's the case then I don't know. If the device is just bridging Frame Relay or ATM over to an ethernet interface then you can just use the ethernet method.
The only way I'd know around the PPPoE issue would be too go buy one of those Cable/DSL gateway devices like a Netgear RT-314, which you can buy for about $20.00 USD right now. Then you wouldn't have to deal with PPPoE directly as that device would take care of that for you.