Connecting it would be pretty straightforward after locating the auxiliary hydraulic system pressure and return ports and the diverter valve. I don't know the tractor, but generally they are under the seat. It's just a matter of connecting the pressure and return lines to the corresponding ports on the splitter control valve. The splitter's reservoir is redundant. To use, the diverer valve is set to aux, which then pressures the splitter but not the 3ph unless the tractor has a combined manifold/diverter. There is an assumption here that the splitter valve is an open centre type.
The connection is feasible and shouldn't damage the system provided the splitter valve contains a properly adjusted pressure relief valve and the tractor’s relief valve ‘sees’ the auxiliary system. The problem is that the splitter's performance is likely to be very slow. Many people say that a 10-gpm flow is needed to run typical sized splitters at acceptable speeds. That's probably why the splitter was connected to PTO pump in the first place.