Keep in mind that WC flies harbor parasites. It is best to get farmed pupae for feeding.
Flies gutload really easy.. they eat anything. I mix up my gutload and then wait for the fly poop to match the color of whatever I am feeding them. I can be reasonably certain that they are very well gutloaded at that point..

The fact that flies will eat anything can be a problem, because they will quite happily eat chameleon poop and anything else yucky that might be in the cage. I feed only a dozen or so at a time to try and avoid that. Plus, if you over do it, the poor chameleons seem to be annoyed by the flies landing on them.
If you don't want flying flies, you can incubate the pupae at a high temp (95-100 degrees) in a container with a layer of wet vermiculate, covered by screen, and then the pupae placed on top of that. Provide only a small vent in the lid to keep the humidity extremely high. The flies hatch and can't dry their wings.. they curl as a result. About 90-95 percent of the flies that hatch will be flightless. Hatch rates are lower when you use this method, though, about 70 percent.
www.spiderpharm.com sells pupae at a very reasonable price.. might want to check and see if they will ship to Canada. Raising flies is pretty easy, too, and doesn't have to be a nasty stinky mess. The trick is to provide lots of air flow.
Heika