1-Plug your drive into your USB port on your computer
2-Open a console (text mode, terminal, konsole, whatever your GUI use, that thing that look like DOS mode)
3- Type "dmesg". You will have a lot of text scrolling by. Only the last few line are important, something that should look like :
SCSI device sda: drive cache: write back
SCSI device sda: 2091050 512-byte hdwr sectors (1071 MB)
4-This tell you the name of the device, in my case, "sda". Note that your lines will be different, of course. To mount something you need 2 things. The name of the device AND the partition number. We already have the name.
5- Type "su - " to login as root in the text mode.
6- Type "cfdisk /dev/THE_DEVICE_YOU_FOUND" (change this line according to your device name)
7- Now you should have a listing of your hard drive partition in front of you. Take note and leave cfdisk
8- We have name and partition number... We can attempt a mount. Syntax of mount command is like "mount /dev/DEVICE_NAMEPARTITION_NUMBER /where/you/want/it". So create yourself a folder (the way you prefer, if you want to use textmode, type "mkdir /folder/you_want_to/create/" )
9- Mount your drive to the folder. In my case, I mount my drive to /mnt/other1 and I only have 1 partition so my mount command is : "mount /dev/sda1 /mnt/other1" but you could (will have to) change it to fit your system
10- Now you should be able to use the drive. Note it may be read-only for normal user, if you made it there, I'll tell you how to change this