Unfortunately, even if you we're to jail break your device, the Cydia tweak AnyAttch is not what you will need in this instance. AnyAttach is for use in e-mail so you can attach a file while composing an e-mail. Besides, AnyAttach is not working on iOS 6 at the moment (we are waiting on an update).
If you were jail broken, the tweak you would use is called "Safari Upload Enabler." This makes it so you can upload files to the Internet. Unfortunately, this tweak is ALSO not updated for use with iOS 6.
So.
Have you looked into using the web browser iCab Mobile? I've not used it for this purpose, but I understand that there is a feature where you can upload documents. I know it's a paid app at the App Store, but I don't remember the price (it's not too expensive, though, that much I do remember).
Maybe give that a try?
Marilyn
P.S. Not that I'm discouraging you from jail breaking your device (I've JB'd mine and love it). It's just that, for right now, if you JB it for the sole purpose of using either of those tweaks, you'll be disappointed...