Hello,
I have just been implementing Teseract into an iOS project, and also worked with Tesseract running on a server and accessible via php, so I should be able to make your Titanium module in just a few days.
I would try to match your current web API perfectly so your code will not need to be changed, or have very minimal changes in order to use the offline OCR system.
Please check my portfolio for examples of other Apps I have made.