Have you tried using optical recognition software to scan the script in? There are some websites that will do it for free. If you use the OCR software to scan the script, I recommend double-checking for errors- sometimes the software doesn't scan everything perfectly. I've also just sucked it up and typed the whole thing during prep week. Labor-intensive and tedious, but the upside is that you become VERY familiar with the script.
I have never used a tablet as an ASM, but I do use a digital calling script. I'd be interested to hear how this works out for you, so I hope you post about your experience!