short answer no.
long answer maybe...
it could be possible with a digital pot and an arduino i guess...
The joysticks are actual analog pots, therefore have a definitive start and end points. a mouse/trackball is an infinitely directional device.
you would need to have the programming of the arduino ignore after a certain amount of pulses then decide if by stopping you "release the stick" back to zero or if you would have to roll it back....then you start getting into situations where it would think the stick is stuck in one direction slightly since the trackball has no frame of reference for what is the middle so then you need to experiment with deadzones and on and on and on.
so ya, short answer no, long answer, plausible.