Mounting USB Drives

I downloaded
http://www.lnx-bbc.org/images/bbc-2.1.iso

and it assigns a lun number to the usb drive but there is no mount.
I have used other usb drives before but for some reason. this usb drive 
does not
show up. How can I  identify the lun # and manually assign a /mnt/usb or 
/dev/sda1

Recently. I was able to purchase a 512Mb usb drive and recover data from a
bad hard drive. I was doing the same tonight and the usb drive is not 
available.
The hard drive can be read but the usb drive is not mounted or accessible.

please advise.

dominic