I don't know why the thread re: 1/8" jacks input to the MBP is closed, but in case the OP still wonders if there is a practical solution to the issue, here is a product:
http://store.apple.com/us/product/TV233LL/A?afid=p210|frgl&cid=AOS-US-SHOP-Froogle
Of course, a dedicated audio interface is definitely preferable especially with a condenser, but since the request was so adamant about not wanting to hear it, this product is $60.
http://store.apple.com/us/product/TV233LL/A?afid=p210|frgl&cid=AOS-US-SHOP-Froogle
Of course, a dedicated audio interface is definitely preferable especially with a condenser, but since the request was so adamant about not wanting to hear it, this product is $60.