Issue tracking with WordPress - User Autosuggest

I've been playing with the awesome theme that is Quality Control by Spencer Finnell. I've created a child theme and made a few modifications to suit my intended use. I wanted to make it easier to link issues to developers without having to know or guess the username, so I implemented an autosuggest!

The shot here is just a design mockup, however I have a working autosuggest implemented which lists the developers (users) in the system - I just need to figure out how to translate this implementation style into code - It's tricky.