Yes I know that rosegarden4 blows away rosegarden2,
 and ALSA is the way to go, but since knoppix includes
 rosegarden2 and OSS, I think it would be easier for me
 to get this working than switch to ALSA and new
 software. 
You can start Knoppix with a 2.6 kernel which includes alsa.
You can run Rosegarden2 with ALSA thanks to the ALSA OSS
emulation.
What I do not know: If the Knoppix 2.6 kernel does
automatically configure ALSA devices or if it simply does use
OSS.
 Best regards
    ce