Enabling sound on your javastation is possible at last. Here's explained how to do it. You'll need a 2.4 kernel, since sound is not yet fixed in linux 2.6.

Proll

The default proll doesn't set up the irq routing for the cs4231 audio chip. So we have to patch the proll.
So get the latest proll from http://people.redhat.com/zaitcev/linux/proll_18.tar.gz and patch it (krups/main.c
and/or krups-ser/main.c) with the patch http://www.dnd.utwente.nl/js/files/javastation-sound-proll-18.diff

Kernel

The kernel patch can be found here: http://www.dnd.utwente.nl/js/files/javastation-sound-linux-2.4.20.diff
(written by Jarno Manninen) Next we have to tell the kernel to actually use this interrupt, so grab
a 2.4.20 kernel and patch drivers/sbus/audio/cs4231.c. If you want the driver as a module you have to
patch arch/sparc/kernel/sparc_ksyms.c too. The patch mentioned above does both for you.

Recompile a new kernel, don't forget make dep!

Enjoy!