Prevent focus from leaving inputfield

The program I'm working on is primarily interacted with via text input. I've been planning on using inputfield for this, but I need to focus to almost always stay on it, regardless of whether the user clicks off off it.

Ideally I would disable all the methods that would take the focus off it, and the focus would only be removed if I explicitly did it via a script.

Alternatively, some direction on making my own text input from the ground up may be a better option. How would I go about listening to and recording all keyboard inputs? If I just knew a way to have the standard input system create/add to a string, I could work out the rest from there.