First and foremost, you need a 2.6 series kernel.
Second, udev must be installed and running. If you don't see the appropriate entry appearing under /dev, then you have mis-configured something. Your kernel must support SCSI in order for USB storage devices to work properly.
Now, with those two items correctly configured, you can automate the mounting of attached USB storage devices with a package called usb-mount:
This is basically a set of scripts which are installed under /etc. I was able to get it working under Slackware pretty easily. It enables you to run whatever command you wish upon insertion or removal of a USB storage device. Using this package, you don't need entries in /etc/fstab for any USB storage devices.