BUS="usb", SYSFS{manufacturer}="IBM", SYSFS{product}="USB 2.0 Memory
Key", NAME="usbkey%n", GROUP="disk", MODE="0660"
The %n in the NAME rule is so that if you have two or more usbkeys in
the system, the first gets the name usbkey1, the next usbkey2 etc (even
with just one, I think you would get usbkey1). Note that the system
will create a usbkey, which is similar to sda for scsi harddisk.
You can make it even more specific (for instance, you want to create a
special node for this specific usbkey) by adding more SYSFS attributes,
for instance the serial, which is specific to each USB device.
Save the rules in /etc/udev/rules.d/00usbkey.rules
The number 00 is important, because you want udev to read your rule
before the default rules (it's a first come, permanent set). You are
also required to have the .rules extension to all your rules, and it
must be in /etc/udev/rules.d (or wherever the udev_rules variable is set
in /etc/udev/udev.conf