Ok, I've installed a full debian arm dist on my central, and I've built a new kernel to support some additional goodies. I'm going off memory here, so I might be leaving something out. If you have troubles, just ask.

Here's how to do it:

1. Read the instructions on how to install a debian system on an empeg player. http://empeg.comms.net/php/showthreaded.php?Cat=&Board=hackers_prog&Number=56359&page=&view=&sb=&o=

I would change the following things with his suggestions...
a. Don't bother with the nfs share, just drop debian onto /drive0/mnt/debian. (This will allow you to do an "upgrade" from the original central install cd and not wipe your debian install - the upgrade completely wipes the root partition but not the drive0 partition)
b. Make sure to setup name resolution:
'cp /drive0/var/resolv.conf /drive0/mnt/debian/etc/'
You can't use dpkg or apt-get without DNS, and apt-get isn't at all clear about why it fails.

Ok, after all that, you should have a working chroot install and apt-get should work. You will likely need to "apt-get install x" for the following packages among others.

zip
unzip
ncurses-base
ncurses-bin
libncurses5-dev
vim (tiny-elvis is the default, and it's rough to use)
binutils
gcc-2.95.x
sshd or telnetd (You will have to download sshd seperate if that's what you want to use. Check the link at the bottom)

After all that, make sure you have telnet (or ssh) running (install it, run /etc/init.d/inetd start, and add a non-root user) because the central screen isn't wide enough to run a "make menuconfig". I'm quite partial to PuTTY as a telnet/ssh client, and the emulation works very well.

FTP the rio kernel source (linux.tgz obtained from the required GPL release up on www.rioaudio.com) to the central.

cd /usr/src/
tar xvfz linux.tgz

That should create a directory /usr/src/linux with the kernel source in it.

vi /usr/src/linux/Makefile
change: CROSS_COMPILE = arm-empeg-linux-
to: CROSS_COMPILE =
(we are native compiling, so no need for that)

vi /usr/src/linux/drivers/char/Makefile
comment out these lines with '#' characters

export-objs += ucb1200_generic.o ucb1200_sa1100.o
obj-$(CONFIG_UCB1200) += ucb1200_generic.o ucb1200_sa1100.o
obj-$(CONFIG_TOUCHSCREEN_UCB1200) += ucb1200_ts.o

These seem to be unneeded touchscreen drivers, and kill the kernel compile.

cd /usr/src/linux
make menuconfig

Your processor is SA1100 based, and it's the "jupiter" implementation. Add what you would like to support.

make clean dep && make bzImage modules modules_install

Keep in mind that this will install your modules into the chrooted environment. You can still insmod them from there though.

I've inserted some newly built kernel modules and they have worked fine. I haven't gotten up the courage yet to install my new bzImage though.

I'm not exactly sure how the boot process works on the central, is it possible to install a boot loader like LILO or grub so that I can choose between known-good and experimental kernels upon boot?

Links:

PuTTY:
http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html
Where to get debian ARM potato dist:
http://archive.debian.org/dists/Debian-2.2/
Where is the base-2.2 file?
http://archive.debian.org/dists/Debian-2.2/main/disks-arm/2.2.25-2001-06-10/
Where to get SSH:
http://security.debian.org/dists/potato/updates/non-free/binary-arm/
Central Source Code:
http://www.digitalnetworksna.com/support/rio/product.asp?prodID=100