Installing hubs on EZ-Lube for the first time.......

If you've gone over all the sealing areas of the new parts, you should be fine using the EZ Lube fittings.

Now whether you really need to use them is another matter. Properly lubed bearings don't really need more grease added unless you're putting on huge yearly mileage. If you're putting on 15,000-20,000 miles per year you may need to add some grease after a couple years. Consider when was the last time you added grease to the wheel bearings in your car or truck.