I actually purchased a subscription to Nintendo Power to get the free disc. The subscription is $20 and you get the Zelda disc. 
Yeah, that seems to be the easiest way to get it.
There was some other way they mentioned of getting it w/out the subscription. But it was more than a little complicated. In fact, I don't even remember all that was involved. It seemed much easier to just get the subscription...
I got lucky and had a friend give me his copy that he got with his 'cube.
