Just a stab at curiosity (I don't have a shiteXbox), but did you try to mount your drive at a mount point?
For example:
in /etc/fstab (should be there if you are running linux):
mkdir /mnt/xbox
mount -t (type) /dev/hdc50 /mnt/xbox
Where (type) is the 'brand' of partition you made. Like I said, I am not familiar with xbox-linux, but the principles are still the same: you have /etc/fstab, and your partitions are defined there. Root can mount, and override partitions, and when you recompile your kernel, you have to include support for the filesystems that you want to mount.