I’m not going to say it would be easy or a drop in mod, but….. it does fit in the same area as the trackball, well the basic area where the track ball is, And would require milling out parts of the case for wire pass through, and possibly removing the lower speaker and it’s mounting “well” just to make room for wires, and probably require you to Mill the face to accept the pad in a fashion that was not totally garbage on esthetic. Would also require a USB hub and a PS2 converter board. And probably some other magic sprinkles to make it fully work. Not that anyone would ever want to do anything like that 
The real question is, Does your track ball work? Perfectly? Every time? Would the effort be worth it to be able to navigate a u Console with one had like you do a traditional Linux system?
P.s the synaptics touch nubs from out of HP laptops are also technically compatible with some frankin-wiring. You just have to find one that lines up with the track ball spot, drill it out and probably make that hole a little bigger. And desolder the smt components where the track ball was….is. you might need to modify the gel pad for the keys to give it enough space. But that is also technically an option.