I don't have the perfect suggestion but it might be your best shot: use a document translator and get yourself close. Then compile the new source and see what breaks. Most likely it will ignore items that are not proper words (like btnOK, etc.)
There are a number of sites out there that use Google Translator. Here is just one random one I chose:
http://www.onlinedoctranslator.com/
If you wanted to build your own translator, you could look at this CodeProject article:
http://www.codeproject.com/KB/IP/GoogleTranslator.aspx
I know that isn't in the scope of your initial question, but since using a translator might be your best option, maybe you could build something to make it work better.
