first, you'd have to be able to immerse the hub -that might be real tough. Second, for the process to work, the rusty areas have to line of sight to the anode/cathode (can't remember which is which - the OTHER metal part). that seems unlikely.
I'm guessing other who have had luck unsticking anything similar have had it work more from the soaking than anything else.
One word on old hubs - not sure of the setup there but I've found that what happens very often is that the axle gets mushroomed slightly from frustrated pounding. If you were to pound the hub itself ONTO the axle - if that's possible with your wheel. That might be a better first step.
Sometimes a hub can seem welded to the axle until you go the other way with it - and it moves much more easily.
I use a heavy machined part - like a thick cup that fits around the axle - makes things a lot easier.
By pushing the hub in, you can usually expose enough of the axle to file it down slightly. Then the wheel can pop right off.