You don't have to fiddle with anything.
At boot if you want to run Knoppix with A.D.R.I.A.N.E. disabled, choose 9.shell and then type 'startx'.
After boot, right-click the Network Manager icon, choose 'edit connections', tab 'DSL', type your login & password, 'ok'. Then click again the Network Manager icon and choose 'ppp0'. You're connected!