hello iki,
thanks a lot for your response
not an expert here,
but having a knoppix prior to 6.0 succesfully connected to the DSL provider via pppoe
and since 6.1 certainly lacks pppoeconf, though modules appear to be there
I tried to force it by manually editing
/etc/ppp/peers/dsl-provider
/etv/ppp/pap - chap - secrets
(as they would work for knoppix_5.x)
then
pon dsl-provider
reported:

Plugin rp-pppoe.so loaded.
Linux kernel does not support PPPoE -- are you running 2.4x?

I must have missed something...

your method works fine
it doesn't even require you boot to console first by knoppix 2

thanks a lot for your time!