I'm pretty sure it won't work; there's nothing special about the point of a pin that would make it more attracted to the extra magnet than the middle of the pin.
I've given this a lot of thought (I love my Zirkel, but it's not as pretty as my old magnetic pin dish). I figure the Zirkel uses magnets that I haven't been able to find for sale on the internet... bar magnets, but with the poles along the sides instead of at the ends. I'm trying to work up the nerve to break open my Zirkel to see if this is true.
Of course, if you have a nice strong magnet, it would be fun to try! Magnets are great toys
