Ah, the downfall of slot drives - getting a disc stuck in it when it dies :(
As per the comment to your question, I presume that this is a smaller CD, not an actual minidisc that is more akin to a floppy disk in a plastic case?
Oddly, some slot loading mechanisms can support these smaller discs. For example, the Nintendo Wii is a vertical slot loader that will accept Gamecube discs that are smaller than regular CDs/DVDs.
Obviously, the MacBook won't tho. I would recommend the use of a pair of slim "shims" that you can use to make a pair of tweezers with. They would need to be both slim, but strong enough to get a grip with. You may need to cover the ends if you don't want to risk scratching the disc.
Alternatively, a piece of double sided sticky tape on the end of a plastic ruler may help. Just insert an inch (don't go too far, don't want to touch the laser with sticky stuff), and wobble it up and down a bit, see if you can get contact with the edge of the disc, then slowly pull it out. If this is tricky, try it with the drive/laptop upside down.