The trackball can be attached to the TT2 interface, but not the other way around. In doing so, you would be limiting the TT2 to the Z-Axis, which, because of the way the OS handles the Z data, is more sensitive than the X or Y without either patching MAME or finding a release that fixes this.
If you are interested in doing this, I can supply a special version of the trackball that will allow a TT2 Slave to attach to the Z axis on the trackball interface. But you would need to specify this in the comments section at the time of checkout.
RandyT