Reinstalling java?
Knoppix 5.0.1 already has this java included
java version "1.4.2_11"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_11-b06)
Java HotSpot(TM) Client VM (build 1.4.2_11-b06, mixed mode)

Are you installing another version or API?
Remastering a whole new java version might be possible.