Sorry that didnt work for you. Were you running virtualbox ose at any time and did you do a clean install of mint 10 and which version? The reason Im asking is that from what I can tell virtualbox ose does not have usb support, but version 3.2.10 does. it can be gotten here:
http://www.virtualbox.org/wiki/Linux_Downloads. when I installed it, it told me to manually use apt to completely remove all instances of ose or it would not install properly. Then I installed the virtualbox dkms from apt to go with it.
Edit... I almost forgot after you start the VM go to
"Devices - "Install Guest Additions".
That way you are sure to get the correct ones for the version you have.
That is how I did it for both Mint 9 Isadora x64 and Mint 9 debian x32
LMDE was more stubborn. I had to reboot to get the permissions to take effect.
and my printer wasnt availible until I shared a folder (dont know whats up whith that)

When you get it working, If you goto the bottom of the VM window where the usb Icon is,
right click the shared folders icon; left click shared folders
a box pops up for adding host folders to share with the VM.
give full rw permissions and make the folders permanant or they wont be there the next time you load the VM
In my xp VM they showup as network folders.
The path would be "My Network Places - Entire Network - VirtualBox Shared Folders - \\Vboxcvr -" your folders
just put a link on the VM desktop, or in the quicklaunch bar if you use seamless mode, for fast access.
In seamless mode only the taskbar appears, the desktop and icons are hidden.
Ill keep checking back here to see if you get it working or not.