Switching OK-Cancel and Cancel-OK to enforce user interaction?

Please don't do this unless you are really, really, really sure it's absolutely required. This is a case of trying to fix carelessness and stupidity by technological means, and that sort of thing almost never works.

What you could do is use verbs or nouns instead of the typical Windows OK / Cancel button captions. That will give you an instant attention benefit without sacrificing predictability.

NOOOOOOOOOOOO!

In one of our products we have a user option to require Ctrl+Click for safety related commands.

But startling the user with buttons that swap place or move around is bad design in my book.