Uhhh no, I think he's talking about using a seperate(sic) cooling circuit for the coolant from the turbos.
So basically adding an additional cooling system, with its own water pump, overflow, radiator, and lines.
It's absolutely possible, though it obviously increases cost and adds failure points to the car. However is it necessary? Remember your turbochargers, like your engine, are supposed to be hot. I always hate the millions of posts about aftermarket oil coolers, radiators, thermostats, and all this shit to make something cold that's supposed to be hot. Unless you are going into limp mode for oil or water temps, leave it the fuck alone. It's supposed to be hot, and in a lot of cases, really fucking hot. Oil doesn't magically turn into dust and blow your motor at 300*. In fact manufacturer testing has shown although high (Over 300) temps reduces oil life, the oil maintains protection standards to well above 300.
Now that being said, we aren't testing water and oil temperatures AT the turbocharger, so inside they are obviously going dramatically higher. We also aren't looking at actual cylinder/piston temperatures. I know of a car that melted the #6 piston on a FBO stock turbo 51,000 mile motor at 19psi after repeated road course laps. During all these laps oil and water temps never exceeded safe operational parameters. Ambient was around 50* which certainly helped keep the oil/water temps in check. But point is the relentless ass-fucking given to the cylinders/pistons melted the #6 down. I am not sure yet if the turbochargers are ok, but I have no reason to believe they aren't. In which case my piston failed before my turbocharger(s) did.
One other thing to consider, adding a separate cooling circuit for the turbochargers will dramatically extend both oil and water temp warm-up time, which is a huge negative. Even if the water system is still thermostatically controlled it will still extend warm-up time. For this reason alone I'd be terrified of doing this.
In summary, you need more data before jumping to doing something like this. That data needs to show the turbo, oil, and/or coolant are vastly exceeding their max temperature. So you need oil temperature readings before and after the turbo, coolant readings before/after, and an overall turbocharger temp reading (Via IR camera would probably work).