First try the PPoE config program in the Knoppix menu.

I suspect that you're trying to "crack" your ISP supplied router so you can use Knoppix and not a windows box with crumby software. Of couse, the ISP supplied software ususally has it's own login to the modem, not YOURS making things twice as hard! You may still be SOL because even if you connect you could be stuck with an AOL-type proprietary protocol that blocks you from connecting.

Robertson [Lindows infamy?] could make a mint just from the ISP and media [DVD!] connectors he's got if he'd package them for purchase by "regular" Linux users. but hey, his loss.