It all hinges upon what integration the actual pad has with a computer.
You can make a CF page where you read a file from disk and file it to a database, that's a walk in the park; owever it's getting that image into CF in the first place. Having never used them, I can only guess but I'd assume they will come with some kind of software. That's the critical bit to establish really; if it just writes a file to disk then that's easy enough, if it can post to a website then even better.
I'd look into how the hardware integrates with a computer before anything.
This isn't really a CF issue. It's a client-side issue. You'll need a client-side solution that can capture the signature, then upload that file along with the additional form data. I've seen some nice Flash/Flex implementations that did this. While looking for that, I stumbled across this:
Dave Watts, CTO, Fig Leaf Software
Read this before you post: