Unfortunately I do not have a simple conversion script. What I do have will not work with Snitz forums in general, as my Snitz forum database schema was modified to an extent. If you are a developer and are interested in seeing the code I have, feel free to send me a PM about this. However be forewarned that it is very much a mess and was not intended on being reused / used by others when I wrote it.
I may work on a proper general conversion script after 1.9.3 final is released, but no promises.