Using OIA extensions to apply visual focus elements to interviews

I'm looking for advise on how to utilize extensions in Intelligent Advisor to apply visual focus elements to an interview for users who are either utilizing a screen reader, due to visual impairments, or who are exclusively utilizing a keyboard (no mouse) to navigate an interview. Currently, when I open an OIA interview within our user interface, there is no visual indicator of where on the screen the user is focused. I've been told that extensions might be a viable option for doing this, but I have no experience utilizing them.