Hi Adam,
Linux kernal version 2.4 and greater should support USB Hard drives.
Try the following, login as 'root' and issue the following commands:
modprobe usb-storage
modprobe ide-scsi
The USB hard drive should be recognized as '/dev/sda' unless you have other SCSI disks attached, then it will take on the next available letter (eg. 'sdb', 'sdc' ...) (USB Storage devices seem to be treated as SCSI devices).
Once it's been recognized, you can 'fdisk' (partition) the drive: '/sbin/fdisk /dev/sda'
Then build the file system: '/sbin/mkfs /dev/sda'.
From there, modify the '/etc/fstab' file and mount the drive.
Cheers.
- Luis.