This is already known, and a bypass method. There is no tried and true methhod to making mirc completly locked without storing the information some where. This was a known bypass method, and there has been arguments of how mirc should change it, though I don't see why. The purpose of locking mIRC is usually so younger siblings can't fool with your mirc as they do not usually know what they are doing and can cause harm. Not many know how to access the registry, I see it completly its purpose.
If you want a safer method, im sure there is a scriptable way you may want to look into.