try this
make the /rmdisk directory
mkdir /rmdisk
then restart the volume management service
/etc/init.d/volmgt stop
/etc/init.d/volmgt start
put in the usb drive
run volcheck
then just cd to /rmdisk
you should see the usb drive mounted to /rmdisk/usb0 or something there about.
If volume management doesn't work you can all ways mount it by hand.
It looks something like this
mount -F pcfs /dev/dsk/c1t0d0s0:c /mnt/usb
for some reason usb drives need to have the :c at the end of the device and slice.
you just need to find out what device in /dev/dsk it is you want to mount.
hope this helps.
heres the link to the sun docs page
http://docs.sun.com/app/docs/doc/817...b+drive&a=view