In case it is useful, about 8 years ago I did some conversions for someone of omnipage OCR XML output to TEI. See zip file at http://james.blushingbunny.net/omnipage2TEI/ I probably wouldn't write it in the same way nowadays (both the xslt and the form of TEI output). Don't know if anyone is using that format any more or not.
Dr James Cummings, [log in to unmask]
School of English Literature, Language, and Linguistics, Newcastle University