Just copied the USB Mass Storage configuration from my laptop (Shrek -- whose display doesn't work anymore, incidentally; I'm really not impressed with Toshiba's last models, but that'll be the subject of a rant some day, probably).
So, I'll record the very complicated operations for posterity:
/dev/sda1 /usb vfat noauto,user 0 0
Then plug in your mass storage and just mount /usb
If you have several SCSI devices, the USB device will probably end up somewhere else. Also, I have a feeling that configuring Shrek had been more complicated. This worked on a modern Debian.