If you don't mind the USB mouse only working in X, then you can do the following.
First, delete the symlink you made to /dev/mouse by doing:
and then making a symlink back to the default mouse by using this command:
Code:
ln -s /dev/psaux /dev/mouse
Next add the following to your xorg.conf file underneath where your your other mouse is configured:
Code:
Section "InputDevice"
Identifier "USBMouse"
Driver "mouse"
Option "Protocol" "IMPS/2"
Option "Device" "/dev/input/mice"
Option "ZAxisMapping" "4 5"
EndSection
Then add the following line to Section "ServerLayout":
Code:
InputDevice "USBMouse" "AlwaysCore"
Make sure the other mouse is set to CorePointer and then this should work.