ignore touchpad if mouse connected

[Sam Halliday]

hi there,

i have my X setup to use /dev/input/mice which reads from the usb mouse or
touchpad. i know how to set up X so that i select only one of these... but i
wish to do something a little more complicated: i want to ignore the touchpad
iff (if and only if) the mouse is connected. is this possible to set up in X? (a
general solution including the console would be acceptable)