Based on work by Myno, andre, mindbender, downlalaway, Thorongil, frontalot, and TcT.
Originally by downlalaway
This is a basic run through of USB devices connecting for Debian on an PPC LinkStation. The USB hard drive is USB 2.0 at 3Mb/s (on a laptop HD). NB. This was based on using the original kernel #990 conversion of the LS 1 and not the Freelink project. It has been updated for use with Freelink 1.11 but requires run-throughs by others to check. USB and hotplug was/is a little flakey on 2.4 kernels in recognising devices. A reboot while the device is in should make things work. The 2.6 debian kernel is highly recommended if hot-swapping of usb devices might occur.
Kernel 2.4 (MIPSel)
apt-get install hotplug autofs usb-utils usbview
Note: If usb-utils doesn't work, try usbutils.
autofs is for file system recognising and hotplug for usb detection is necessary. Usb-utils gives us the lsusb tool for detecting connections and usbview is a gui showing connected devices. Create a mount directory in preparation: I did /mnt/UsbDrive but one can make one in /home/username/. A symlink to the directory you chose as mount point from a directory that you already share through samba should allow it to share (unless you've modified samba to prevent this).
Note: This is for brief usb disk mounting. For repetitive use go straight to the Automount section since this work very well especially with kernel 2.6. All usb devices can need reboots with 2.4.17, but this is due to the kernel only.
Might be worth a chmod permissions modification if you want to share it with samba or use for backups (haven't used it too much yet).
mount -t vfat /dev/sda /mnt/UsbDrive
Of course, replace vfat for whatever your partition type is.
Enjoy and please carefully comment if it doesn't work or changes needed.