Mr. Beer seems to be notorious for sub-par kits. They are more like training aids for new brewers. Trying to prime with what you suggested MAY work but i see two potential problems. First, everything youve suggested has a much higher amount of unfermentables (corn sugar is almost all dextrose which is very fermentable) in it so you need to compensate by adding more to get the required amount of prime from it. Second, by having to compensate by adding more, you may run the risk of changing the beers flavor in a bad way. So look at it this way. You could either play it safe and have a weak beer, or take a chance and experiment, you may get lucky. I suggest the later. Sure theres risk involved, but its BREWING! Its fun to go out of your comfort zone and try new stuff. Let me know how it turns out. Good luck!