Ok I snuck this in and here's what I was able to determine.
I wasn't able to get AutoComplete against AD to work _at_all_
I did however get it working with a database really quickly. By using an autocomplete text box, configuring it to use an input on the FIRST_NAME column of my database (stores employee data), and setting the input to completion_prefix% with a dynamic value setting.
You can see here it found several employees with the first name like 'cal%'
And here is my setup for the component itself.
I did not have to put this inside a dynamic update panel or make it post form on value change. Sorry I couldn't help out much with the AD piece.