I was not able to find a VBA solution for this problem on Mac Excel. There simply seemed to be no way to output UTF-8 text.
So I finally had to give up on VBA, bit the bullet, and learned AppleScript. It wasn't nearly as bad as I had thought.
Solution is described here:
http://talesoftech.blogspot.com/2011/05/excel-on-mac-goodbye-vba-hello.html