If his eggs turned out hard as a rock, he over brined them. It is a good cure.
Pro cure wizard is a hot cure; it has a lot of sodium sulfite in it and is better for Chinook (Springs). Coho and steelhead normally prefer a more natural egg. For Coho and some steelhead fishing I use a light curing of Pro Cure Redd Hott Double Stuff. For just steelhead eggs I use plain borax.
If you're a serious egg fisherman keep rubber gloves, paper towels and zip lock bags in your vest. When you catch a fish, bleed it immediately by popping some gills on each side of the fish and placing it back in the water to bleed out. Make sure the heart is still pumping and bleed out completely. If the fish is caught in a river, I don't harvest the eggs until I'm ready to leave because there are no digestive enzymes to worry about and the eggs are safe inside the fish. Just make sure to keep the fish cool. They should be blood free when you remove them and make sure you don't allow them contact with the water. Wrap them in the paper towel, and place them in the plastic bag and keep cool. PS, if you're really hard core, make sure your paper towels are unbleached.
I used to use the jar method. I use wide mouth jars that allow me to vacuum seal them when finished. When you get home, butterfly your eggs. If from a large fish, I cut the skein halves into halves or thirds. I use about half the amount of cure than the bottle recommends when I'm curing eggs for Coho. I add a light sprinkling of cure, then add a piece of the eggs, then another light sprinkle, then more eggs etc, etc, etc. until I've either filled the jar or run out of eggs. Give another light sprinkling on top if there's no cure there already. Then I seal the jars and shake/roll the cure and eggs together to make sure the cure gets into all the nooks and crannies.
After about an hour the eggs should be nice and juiced up. Then I add a couple of drops of pro cure anise+ scent directly to the juice and roll it all in nice and good. Keep the eggs in a cool place for the next day or so making sure you flip the jar every couple of hours. After a day, most of the juice has been re absorbed. Pour the remaining juice into a separate container (its killer for curing prawns, shrimp and sardine fillets. I know you can't use sardines in Canada, but try curing salad shrimp/prawns in the juice
) Now you can either dry the eggs out over a screen until they're how you like them, or vacuum seal and freeze just like they are, or fish immediately. Sometimes, I'll also store them in layers of borax if I want to toughen up the skein for fishing in fast water.
There you have it, eggs that have accounted for several six fish limits when we had them down in Washington. The key is to avoid scent/water contamination of the eggs, keep the blood out, and to tailor your cure to the fish you're trying to catch. But the cure you use isn't as important as the quality of the egg you cure.
For a nice tutorial with lots of pictures on egg curing follow this link:
http://www.ifish.net/amercure1.html