In order for tethering to work, your iPhone must actually have the tethering option enabled. This depends on your network carrier and contract. For iPhone 3.0 OS you can also just install a so-called mobileconfig profile which enables tethering, but this in a gray zone legally.
The following tutorial will explain how to extract all text from PDFs (including text in images), by using a combination of Ghostscript and a command line OCR tool called tesseract-ocr.
Tips for audio and video tagging for iPhone / iPod Touch under Linux.