After doing it once manually and looking at three more wikis to convert, I decided to write a Ruby script to speed up the process.
The script took about one hour to write, and is not an elegant solution, but it worked for me. Perhaps it will work for you, or more likely, you can fork it (its GPL), improve it, and make it work for you, and potentially more people besides the two of us.
It uses Grit to interface with the git repository.
Enjoy!