The first step is to see if your card is detected by default. If not, you'll have to tinker a bit and either hunt down a linux driver or use something like ndiswrapper. The chances are pretty good the card will be up and running from the get-go, unless you've got one from broadcom or somebody else who doesn't have great linux support for their stuff. After that you can take a peek at two packages, pppoe and pppoeconf. The first of those is the driver for pppoe connections, the second is the initial config tool used to set your connection up. I haven't used either of those so I don't know how good they are, but that looks like the way this sort of thing is usually done.
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Containment BreachDo not meddle in the affairs of archers, for they are subtle and quick to anger.